diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index 08dec5ee7..078b8f400 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -2951,13 +2951,46 @@
     "message": "Emoji",
     "description": "Label for emoji button"
   },
+
+  "ErrorModal--title": {
+    "message": "Something went wrong!",
+    "description": "Title of pop-up dialog when user-initiated task has gone wrong"
+  },
+  "ErrorModal--description": {
+    "message": "Please try again or contact support.",
+    "description": "Description text in pop-up dialog when user-initiated task has gone wrong"
+  },
+  "ErrorModal--buttonText": {
+    "message": "Okay",
+    "description": "Button to dismiss pop-up dialog when user-initiated task has gone wrong"
+  },
+
   "GroupV2--admin": {
     "message": "Admin",
     "description": "Shown next to the set of administrators in a group"
   },
-  "GroupV2--timerConflict": {
-    "message": "Failed to update disappearing message timer. Please try again later.",
-    "description": "Shown if the user runs into a group update conflict attempting to update a GroupV2 message timer"
+  "updating": {
+    "message": "Updating...",
+    "description": "Shown along with a spinner when an update operation takes longer than one second"
+  },
+
+  "GroupV2--create--you": {
+    "message": "You created the group.",
+    "description": "Shown in timeline or conversation preview when v2 group changes"
+  },
+  "GroupV2--create--other": {
+    "message": "$memberName$ created the group.",
+    "description": "Shown in timeline or conversation preview when v2 group changes",
+    "placeholders": {
+      "memberName": {
+        "content": "$1",
+        "example": "Bob"
+      }
+    }
+  },
+  "GroupV2--create--unknown": {
+    "message": "The group was created.",
+    "description": "Shown in timeline or conversation preview when v2 group changes"
   },
   "GroupV2--title--change--other": {
     "message": "$memberName$ changed the group name to \"$newTitle$\".",
@@ -3253,7 +3286,7 @@
     "description": "Shown in timeline or conversation preview when v2 group changes"
   },
   "GroupV2--member-add--you--unknown": {
-    "message": "A member added you to the group.",
+    "message": "You were added to the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes"
   },
   "GroupV2--member-remove--other--other": {
@@ -3271,7 +3304,7 @@
     }
   },
   "GroupV2--member-remove--other--self": {
-    "message": "$memberName$ left.",
+    "message": "$memberName$ left the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes",
     "placeholders": {
       "memberName": {
@@ -3311,11 +3344,11 @@
     }
   },
   "GroupV2--member-remove--you--you": {
-    "message": "You left.",
+    "message": "You left the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes"
   },
   "GroupV2--member-remove--you--unknown": {
-    "message": "A member removed you.",
+    "message": "You were removed from the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes"
   },
 
@@ -3437,7 +3470,7 @@
     }
   },
   "GroupV2--pending-add--one--other--unknown": {
-    "message": "A member invited 1 person to the group.",
+    "message": "One person was invited to the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes",
     "placeholders": {
       "inviteeName": {
@@ -3457,7 +3490,7 @@
     }
   },
   "GroupV2--pending-add--one--you--unknown": {
-    "message": "A member invited you to the group.",
+    "message": "You were invited to the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes"
   },
   "GroupV2--pending-add--many--other": {
@@ -3485,7 +3518,7 @@
     }
   },
   "GroupV2--pending-add--many--unknown": {
-    "message": "A member invited $count$ people to the group.",
+    "message": "$count$ people were invited to the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes",
     "placeholders": {
       "count": {
@@ -3515,6 +3548,10 @@
       }
     }
   },
+  "GroupV2--pending-remove--decline--from-you": {
+    "message": "You declined the invitation to the group.",
+    "description": "Shown in timeline or conversation preview when v2 group changes"
+  },
   "GroupV2--pending-remove--decline--unknown": {
     "message": "1 person declined their invitation to the group.",
     "description": "Shown in timeline or conversation preview when v2 group changes"
@@ -3539,6 +3576,26 @@
       }
     }
   },
+  "GroupV2--pending-remove--revoke-own--to-you": {
+    "message": "$inviterName$ revoked their invitation to you.",
+    "description": "Shown in timeline or conversation preview when v2 group changes",
+    "placeholders": {
+      "inviterName": {
+        "content": "$1",
+        "example": "Bob"
+      }
+    }
+  },
+  "GroupV2--pending-remove--revoke-own--unknown": {
+    "message": "$inviterName$ revoked their invitation to 1 person.",
+    "description": "Shown in timeline or conversation preview when v2 group changes",
+    "placeholders": {
+      "inviterName": {
+        "content": "$1",
+        "example": "Bob"
+      }
+    }
+  },
   "GroupV2--pending-remove--revoke--one--unknown": {
     "message": "An admin revoked an invitation to the group for 1 person.",
     "description": "Shown in timeline or conversation preview when v2 group changes",
diff --git a/js/modules/signal.js b/js/modules/signal.js
index cf485cabf..578e50c80 100644
--- a/js/modules/signal.js
+++ b/js/modules/signal.js
@@ -28,6 +28,7 @@ const {
   AttachmentList,
 } = require('../../ts/components/conversation/AttachmentList');
 const { CaptionEditor } = require('../../ts/components/CaptionEditor');
+const { ConfirmationModal } = require('../../ts/components/ConfirmationModal');
 const {
   ContactDetail,
 } = require('../../ts/components/conversation/ContactDetail');
@@ -36,6 +37,7 @@ const {
   ConversationHeader,
 } = require('../../ts/components/conversation/ConversationHeader');
 const { Emojify } = require('../../ts/components/conversation/Emojify');
+const { ErrorModal } = require('../../ts/components/ErrorModal');
 const { Lightbox } = require('../../ts/components/Lightbox');
 const { LightboxGallery } = require('../../ts/components/LightboxGallery');
 const {
@@ -45,6 +47,7 @@ const {
   MessageDetail,
 } = require('../../ts/components/conversation/MessageDetail');
 const { Quote } = require('../../ts/components/conversation/Quote');
+const { ProgressModal } = require('../../ts/components/ProgressModal');
 const {
   SafetyNumberChangeDialog,
 } = require('../../ts/components/SafetyNumberChangeDialog');
@@ -289,16 +292,19 @@ exports.setup = (options = {}) => {
   const Components = {
     AttachmentList,
     CaptionEditor,
+    ConfirmationModal,
     ContactDetail,
     ContactListItem,
     ConversationHeader,
     Emojify,
+    ErrorModal,
     getCallingNotificationText,
     Lightbox,
     LightboxGallery,
     MediaGallery,
     MessageDetail,
     Quote,
+    ProgressModal,
     SafetyNumberChangeDialog,
     StagedLinkPreview,
     Types: {
diff --git a/stylesheets/_modules.scss b/stylesheets/_modules.scss
index 8880589a0..4510dc605 100644
--- a/stylesheets/_modules.scss
+++ b/stylesheets/_modules.scss
@@ -5293,6 +5293,18 @@ button.module-image__border-overlay:focus {
   }
 }
 
+.module-spinner__circle--on-progress-dialog {
+  @include light-theme {
+    background-color: $color-white;
+  }
+  @include dark-theme {
+    background-color: $color-gray-80;
+  }
+}
+.module-spinner__arc--on-progress-dialog {
+  background-color: $ultramarine-ui-light;
+}
+
 // Module: Highlighted Message Body
 
 .module-message-body__highlight {
@@ -6659,7 +6671,6 @@ button.module-image__border-overlay:focus {
   border-top: 1px solid $color-gray-05;
   display: flex;
   justify-content: flex-end;
-  margin-bottom: -18px;
   margin-left: -16px;
   margin-right: -16px;
   margin-top: -14px;
@@ -7808,10 +7819,11 @@ button.module-image__border-overlay:focus {
 
     &__content {
       @include font-body-1;
-      margin-bottom: 22px;
     }
 
     &__buttons {
+      margin-top: 22px;
+
       display: flex;
       flex-direction: row;
       justify-content: flex-end;
@@ -9276,6 +9288,60 @@ button.module-image__border-overlay:focus {
   margin-right: auto;
 }
 
+// Module: Progress Dialog
+
+.module-progress-dialog {
+  width: 138px;
+  padding: 18px;
+  border-radius: 8px;
+  @include popper-shadow();
+
+  display: flex;
+  flex-direction: column;
+  justify-content: center;
+  align-items: center;
+
+  @include light-theme() {
+    background: $color-white;
+    color: $color-gray-90;
+  }
+
+  @include dark-theme() {
+    background: $color-gray-80;
+    color: $color-gray-05;
+  }
+}
+
+.module-progress-dialog__spinner {
+  padding: 10px;
+}
+
+.module-progress-dialog__text {
+  @include font-body-2;
+}
+
+.module-progress-dialog__overlay {
+  background: $color-black-alpha-40;
+  position: fixed;
+  left: 0;
+  top: 0;
+  width: 100vw;
+  height: 100vh;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  z-index: 5;
+}
+
+// Module: Error Modal
+
+.module-error-modal__button-container {
+  margin-top: 10px;
+  display: flex;
+  flex-direction: row;
+  justify-content: flex-end;
+}
+
 /* Third-party module: react-tooltip-lite */
 
 .react-tooltip-lite {
diff --git a/ts/background.ts b/ts/background.ts
index 720e733bc..43cbba723 100644
--- a/ts/background.ts
+++ b/ts/background.ts
@@ -2546,6 +2546,9 @@ type WhatIsThis = typeof window.WhatIsThis;
     if (message.groupV2) {
       const { id } = message.groupV2;
       const conversationId = window.ConversationController.ensureGroup(id, {
+        // Note: We don't set active_at, because we don't want the group to show until
+        //   we have information about it beyond these initial details.
+        //   see maybeUpdateGroup().
         groupVersion: 2,
         masterKey: message.groupV2.masterKey,
         secretParams: message.groupV2.secretParams,
diff --git a/ts/components/ErrorModal.stories.tsx b/ts/components/ErrorModal.stories.tsx
new file mode 100644
index 000000000..4ab9f1242
--- /dev/null
+++ b/ts/components/ErrorModal.stories.tsx
@@ -0,0 +1,35 @@
+import * as React from 'react';
+import { storiesOf } from '@storybook/react';
+import { text } from '@storybook/addon-knobs';
+import { action } from '@storybook/addon-actions';
+
+import { PropsType, ErrorModal } from './ErrorModal';
+
+import { setup as setupI18n } from '../../js/modules/i18n';
+import enMessages from '../../_locales/en/messages.json';
+
+const i18n = setupI18n('en', enMessages);
+
+const createProps = (overrideProps: Partial<PropsType> = {}): PropsType => ({
+  title: text('title', overrideProps.title || ''),
+  description: text('description', overrideProps.description || ''),
+  buttonText: text('buttonText', overrideProps.buttonText || ''),
+  i18n,
+  onClose: action('onClick'),
+});
+
+storiesOf('Components/ErrorModal', module).add('Normal', () => {
+  return <ErrorModal {...createProps()} />;
+});
+
+storiesOf('Components/ErrorModal', module).add('Custom Strings', () => {
+  return (
+    <ErrorModal
+      {...createProps({
+        title: 'Real bad!',
+        description: 'Just avoid that next time, kay?',
+        buttonText: 'Fine',
+      })}
+    />
+  );
+});
diff --git a/ts/components/ErrorModal.tsx b/ts/components/ErrorModal.tsx
new file mode 100644
index 000000000..65bc30dd7
--- /dev/null
+++ b/ts/components/ErrorModal.tsx
@@ -0,0 +1,46 @@
+import * as React from 'react';
+
+import { LocalizerType } from '../types/Util';
+import { ConfirmationModal } from './ConfirmationModal';
+
+export type PropsType = {
+  buttonText: string;
+  description: string;
+  title: string;
+
+  onClose: () => void;
+  i18n: LocalizerType;
+};
+
+function focusRef(el: HTMLElement | null) {
+  if (el) {
+    el.focus();
+  }
+}
+
+export const ErrorModal = (props: PropsType): JSX.Element => {
+  const { buttonText, description, i18n, onClose, title } = props;
+
+  return (
+    <ConfirmationModal
+      actions={[]}
+      title={title || i18n('ErrorModal--title')}
+      i18n={i18n}
+      onClose={onClose}
+    >
+      <div className="module-error-modal__description">
+        {description || i18n('ErrorModal--description')}
+      </div>
+      <div className="module-error-modal__button-container">
+        <button
+          type="button"
+          className="module-confirmation-dialog__container__buttons__button"
+          onClick={onClose}
+          ref={focusRef}
+        >
+          {buttonText || i18n('ErrorModal--buttonText')}
+        </button>
+      </div>
+    </ConfirmationModal>
+  );
+};
diff --git a/ts/components/ProgressDialog.stories.tsx b/ts/components/ProgressDialog.stories.tsx
new file mode 100644
index 000000000..b17b84fd5
--- /dev/null
+++ b/ts/components/ProgressDialog.stories.tsx
@@ -0,0 +1,21 @@
+import * as React from 'react';
+
+import { storiesOf } from '@storybook/react';
+import { ProgressDialog, PropsType } from './ProgressDialog';
+import { setup as setupI18n } from '../../js/modules/i18n';
+
+import enMessages from '../../_locales/en/messages.json';
+
+const story = storiesOf('Components/ProgressDialog', module);
+
+const i18n = setupI18n('en', enMessages);
+
+const createProps = (): PropsType => ({
+  i18n,
+});
+
+story.add('Normal', () => {
+  const props = createProps();
+
+  return <ProgressDialog {...props} />;
+});
diff --git a/ts/components/ProgressDialog.tsx b/ts/components/ProgressDialog.tsx
new file mode 100644
index 000000000..3d001815d
--- /dev/null
+++ b/ts/components/ProgressDialog.tsx
@@ -0,0 +1,18 @@
+import * as React from 'react';
+import { LocalizerType } from '../types/Util';
+import { Spinner } from './Spinner';
+
+export type PropsType = {
+  readonly i18n: LocalizerType;
+};
+
+export const ProgressDialog = React.memo(({ i18n }: PropsType) => {
+  return (
+    <div className="module-progress-dialog">
+      <div className="module-progress-dialog__spinner">
+        <Spinner svgSize="normal" size="39px" direction="on-progress-dialog" />
+      </div>
+      <div className="module-progress-dialog__text">{i18n('updating')}</div>
+    </div>
+  );
+});
diff --git a/ts/components/ProgressModal.stories.tsx b/ts/components/ProgressModal.stories.tsx
new file mode 100644
index 000000000..f4254755b
--- /dev/null
+++ b/ts/components/ProgressModal.stories.tsx
@@ -0,0 +1,13 @@
+import * as React from 'react';
+import { storiesOf } from '@storybook/react';
+
+import { ProgressModal } from './ProgressModal';
+
+import { setup as setupI18n } from '../../js/modules/i18n';
+import enMessages from '../../_locales/en/messages.json';
+
+const i18n = setupI18n('en', enMessages);
+
+storiesOf('Components/ProgressModal', module).add('Normal', () => {
+  return <ProgressModal i18n={i18n} />;
+});
diff --git a/ts/components/ProgressModal.tsx b/ts/components/ProgressModal.tsx
new file mode 100644
index 000000000..884264c63
--- /dev/null
+++ b/ts/components/ProgressModal.tsx
@@ -0,0 +1,35 @@
+import * as React from 'react';
+import { createPortal } from 'react-dom';
+import { ProgressDialog } from './ProgressDialog';
+import { LocalizerType } from '../types/Util';
+
+export type PropsType = {
+  readonly i18n: LocalizerType;
+};
+
+export const ProgressModal = React.memo(({ i18n }: PropsType) => {
+  const [root, setRoot] = React.useState<HTMLElement | null>(null);
+
+  // Note: We explicitly don't register for user interaction here, since this dialog
+  //   cannot be dismissed.
+
+  React.useEffect(() => {
+    const div = document.createElement('div');
+    document.body.appendChild(div);
+    setRoot(div);
+
+    return () => {
+      document.body.removeChild(div);
+      setRoot(null);
+    };
+  }, []);
+
+  return root
+    ? createPortal(
+        <div role="presentation" className="module-progress-dialog__overlay">
+          <ProgressDialog i18n={i18n} />
+        </div>,
+        root
+      )
+    : null;
+});
diff --git a/ts/components/Spinner.tsx b/ts/components/Spinner.tsx
index 787f8334c..4cdbfa1ae 100644
--- a/ts/components/Spinner.tsx
+++ b/ts/components/Spinner.tsx
@@ -8,6 +8,7 @@ export const SpinnerDirections = [
   'outgoing',
   'incoming',
   'on-background',
+  'on-progress-dialog',
 ] as const;
 export type SpinnerDirection = typeof SpinnerDirections[number];
 
diff --git a/ts/components/conversation/GroupV2Change.stories.tsx b/ts/components/conversation/GroupV2Change.stories.tsx
index 351fd8436..0263c09cf 100644
--- a/ts/components/conversation/GroupV2Change.stories.tsx
+++ b/ts/components/conversation/GroupV2Change.stories.tsx
@@ -81,6 +81,35 @@ storiesOf('Components/Conversation/GroupV2Change', module)
       </>
     );
   })
+  .add('Create', () => {
+    return (
+      <>
+        {renderChange({
+          from: OUR_ID,
+          details: [
+            {
+              type: 'create',
+            },
+          ],
+        })}
+        {renderChange({
+          from: CONTACT_A,
+          details: [
+            {
+              type: 'create',
+            },
+          ],
+        })}
+        {renderChange({
+          details: [
+            {
+              type: 'create',
+            },
+          ],
+        })}
+      </>
+    );
+  })
   .add('Title', () => {
     return (
       <>
@@ -784,6 +813,28 @@ storiesOf('Components/Conversation/GroupV2Change', module)
             },
           ],
         })}
+
+        {renderChange({
+          from: CONTACT_B,
+          details: [
+            {
+              type: 'pending-remove-one',
+              conversationId: OUR_ID,
+              inviter: CONTACT_B,
+            },
+          ],
+        })}
+        {renderChange({
+          from: CONTACT_A,
+          details: [
+            {
+              type: 'pending-remove-one',
+              conversationId: CONTACT_B,
+              inviter: CONTACT_A,
+            },
+          ],
+        })}
+
         {renderChange({
           from: CONTACT_C,
           details: [
diff --git a/ts/components/conversation/StagedLinkPreview.stories.tsx b/ts/components/conversation/StagedLinkPreview.stories.tsx
index b7470b55b..16902d093 100644
--- a/ts/components/conversation/StagedLinkPreview.stories.tsx
+++ b/ts/components/conversation/StagedLinkPreview.stories.tsx
@@ -65,10 +65,6 @@ story.add('No Image', () => {
   return <StagedLinkPreview {...createProps()} />;
 });
 
-story.add('No Image', () => {
-  return <StagedLinkPreview {...createProps()} />;
-});
-
 story.add('Image', () => {
   const props = createProps({
     image: createAttachment({
@@ -102,18 +98,6 @@ story.add('No Image, Long Title With Description', () => {
   return <StagedLinkPreview {...props} />;
 });
 
-story.add('Image, Long Title With Description', () => {
-  const props = createProps({
-    title: LONG_TITLE,
-    image: createAttachment({
-      url: '/fixtures/kitten-4-112-112.jpg',
-      contentType: 'image/jpeg' as MIMEType,
-    }),
-  });
-
-  return <StagedLinkPreview {...props} />;
-});
-
 story.add('No Image, Long Title Without Description', () => {
   const props = createProps({
     title: LONG_TITLE,
@@ -123,7 +107,7 @@ story.add('No Image, Long Title Without Description', () => {
   return <StagedLinkPreview {...props} />;
 });
 
-story.add('Image, Long Title With Description', () => {
+story.add('Image, Long Title Without Description', () => {
   const props = createProps({
     title: LONG_TITLE,
     image: createAttachment({
diff --git a/ts/groupChange.ts b/ts/groupChange.ts
index 7802dcba1..ec0109594 100644
--- a/ts/groupChange.ts
+++ b/ts/groupChange.ts
@@ -52,6 +52,17 @@ export function renderChangeDetail(
   } = options;
   const fromYou = Boolean(from && from === ourConversationId);
 
+  if (detail.type === 'create') {
+    if (fromYou) {
+      return renderString('GroupV2--create--you', i18n);
+    }
+    if (from) {
+      return renderString('GroupV2--create--other', i18n, {
+        memberName: renderContact(from),
+      });
+    }
+    return renderString('GroupV2--create--unknown', i18n);
+  }
   if (detail.type === 'title') {
     const { newTitle } = detail;
 
@@ -406,10 +417,12 @@ export function renderChangeDetail(
   } else if (detail.type === 'pending-remove-one') {
     const { inviter, conversationId } = detail;
     const weAreInviter = Boolean(inviter && inviter === ourConversationId);
+    const weAreInvited = conversationId === ourConversationId;
     const sentByInvited = Boolean(from && from === conversationId);
+    const sentByInviter = Boolean(from && inviter && from === inviter);
 
     if (weAreInviter) {
-      if (inviter && sentByInvited) {
+      if (sentByInvited) {
         return renderString('GroupV2--pending-remove--decline--you', i18n, [
           renderContact(conversationId),
         ]);
@@ -438,6 +451,9 @@ export function renderChangeDetail(
       );
     }
     if (sentByInvited) {
+      if (fromYou) {
+        return renderString('GroupV2--pending-remove--decline--from-you', i18n);
+      }
       if (inviter) {
         return renderString('GroupV2--pending-remove--decline--other', i18n, [
           renderContact(inviter),
@@ -445,6 +461,20 @@ export function renderChangeDetail(
       }
       return renderString('GroupV2--pending-remove--decline--unknown', i18n);
     }
+    if (inviter && sentByInviter) {
+      if (weAreInvited) {
+        return renderString(
+          'GroupV2--pending-remove--revoke-own--to-you',
+          i18n,
+          [renderContact(inviter)]
+        );
+      }
+      return renderString(
+        'GroupV2--pending-remove--revoke-own--unknown',
+        i18n,
+        [renderContact(inviter)]
+      );
+    }
     if (inviter) {
       if (fromYou) {
         return renderString(
diff --git a/ts/groups.ts b/ts/groups.ts
index 8ba526d86..93a0ee303 100644
--- a/ts/groups.ts
+++ b/ts/groups.ts
@@ -20,6 +20,7 @@ import {
   MessageAttributesType,
 } from './model-types.d';
 import {
+  createProfileKeyCredentialPresentation,
   decryptGroupBlob,
   decryptProfileKey,
   decryptProfileKeyCredentialPresentation,
@@ -28,9 +29,11 @@ import {
   deriveGroupPublicParams,
   deriveGroupSecretParams,
   encryptGroupBlob,
+  encryptUuid,
   getAuthCredentialPresentation,
   getClientZkAuthOperations,
   getClientZkGroupCipher,
+  getClientZkProfileOperations,
 } from './util/zkgroup';
 import {
   arrayBufferToBase64,
@@ -51,6 +54,9 @@ import { GroupCredentialsType } from './textsecure/WebAPI';
 import { CURRENT_SCHEMA_VERSION as MAX_MESSAGE_SCHEMA } from '../js/modules/types/message';
 import { ConversationModel } from './models/conversations';
 
+export type GroupV2AccessCreateChangeType = {
+  type: 'create';
+};
 export type GroupV2AccessAttributesChangeType = {
   type: 'access-attributes';
   newPrivilege: number;
@@ -112,6 +118,7 @@ export type GroupV2PendingRemoveManyChangeType = {
 };
 
 export type GroupV2ChangeDetailType =
+  | GroupV2AccessCreateChangeType
   | GroupV2TitleChangeType
   | GroupV2AvatarChangeType
   | GroupV2AccessAttributesChangeType
@@ -156,7 +163,7 @@ export const MASTER_KEY_LENGTH = 32;
 const TEMPORAL_AUTH_REJECTED_CODE = 401;
 const GROUP_ACCESS_DENIED_CODE = 403;
 
-// Group Changes
+// Group Modifications
 
 export function buildDisappearingMessagesTimerChange({
   expireTimer,
@@ -189,6 +196,91 @@ export function buildDisappearingMessagesTimerChange({
   return actions;
 }
 
+export function buildDeletePendingMemberChange({
+  uuid,
+  group,
+}: {
+  uuid: string;
+  group: ConversationAttributesType;
+}): GroupChangeClass.Actions {
+  const actions = new window.textsecure.protobuf.GroupChange.Actions();
+
+  if (!group.secretParams) {
+    throw new Error(
+      'buildDeletePendingMemberChange: group was missing secretParams!'
+    );
+  }
+  const clientZkGroupCipher = getClientZkGroupCipher(group.secretParams);
+  const uuidCipherTextBuffer = encryptUuid(clientZkGroupCipher, uuid);
+
+  const deletePendingMember = new window.textsecure.protobuf.GroupChange.Actions.DeletePendingMemberAction();
+  deletePendingMember.deletedUserId = uuidCipherTextBuffer;
+
+  actions.version = (group.revision || 0) + 1;
+  actions.deletePendingMembers = [deletePendingMember];
+
+  return actions;
+}
+
+export function buildDeleteMemberChange({
+  uuid,
+  group,
+}: {
+  uuid: string;
+  group: ConversationAttributesType;
+}): GroupChangeClass.Actions {
+  const actions = new window.textsecure.protobuf.GroupChange.Actions();
+
+  if (!group.secretParams) {
+    throw new Error('buildDeleteMemberChange: group was missing secretParams!');
+  }
+  const clientZkGroupCipher = getClientZkGroupCipher(group.secretParams);
+  const uuidCipherTextBuffer = encryptUuid(clientZkGroupCipher, uuid);
+
+  const deleteMember = new window.textsecure.protobuf.GroupChange.Actions.DeleteMemberAction();
+  deleteMember.deletedUserId = uuidCipherTextBuffer;
+
+  actions.version = (group.revision || 0) + 1;
+  actions.deleteMembers = [deleteMember];
+
+  return actions;
+}
+
+export function buildPromoteMemberChange({
+  group,
+  profileKeyCredentialBase64,
+  serverPublicParamsBase64,
+}: {
+  group: ConversationAttributesType;
+  profileKeyCredentialBase64: string;
+  serverPublicParamsBase64: string;
+}): GroupChangeClass.Actions {
+  const actions = new window.textsecure.protobuf.GroupChange.Actions();
+
+  if (!group.secretParams) {
+    throw new Error(
+      'buildDisappearingMessagesTimerChange: group was missing secretParams!'
+    );
+  }
+  const clientZkProfileCipher = getClientZkProfileOperations(
+    serverPublicParamsBase64
+  );
+
+  const presentation = createProfileKeyCredentialPresentation(
+    clientZkProfileCipher,
+    profileKeyCredentialBase64,
+    group.secretParams
+  );
+
+  const promotePendingMember = new window.textsecure.protobuf.GroupChange.Actions.PromotePendingMemberAction();
+  promotePendingMember.presentation = presentation;
+
+  actions.version = (group.revision || 0) + 1;
+  actions.promotePendingMembers = [promotePendingMember];
+
+  return actions;
+}
+
 export async function uploadGroupChange({
   actions,
   group,
@@ -309,11 +401,7 @@ export async function maybeUpdateGroup({
     // Ensure we have the credentials we need before attempting GroupsV2 operations
     await maybeFetchNewCredentials();
 
-    const {
-      newAttributes,
-      groupChangeMessages,
-      members,
-    } = await getGroupUpdates({
+    const updates = await getGroupUpdates({
       group: conversation.attributes,
       serverPublicParamsBase64: window.getServerPublicParams(),
       newRevision,
@@ -321,48 +409,7 @@ export async function maybeUpdateGroup({
       dropInitialJoinMessage,
     });
 
-    conversation.set(newAttributes);
-
-    // Ensure that all generated messages are ordered properly.
-    // Before the provided timestamp so update messages appear before the
-    //   initiating message, or after now().
-    let syntheticTimestamp = receivedAt
-      ? receivedAt - (groupChangeMessages.length + 1)
-      : Date.now();
-    // Save all synthetic messages describing group changes
-    const changeMessagesToSave = groupChangeMessages.map(changeMessage => {
-      // We do this to preserve the order of the timeline
-      syntheticTimestamp += 1;
-
-      return {
-        ...changeMessage,
-        conversationId: conversation.id,
-        received_at: syntheticTimestamp,
-        sent_at: sentAt,
-      };
-    });
-
-    if (changeMessagesToSave.length > 0) {
-      await window.Signal.Data.saveMessages(changeMessagesToSave, {
-        forceSave: true,
-      });
-      changeMessagesToSave.forEach(changeMessage => {
-        const model = new window.Whisper.Message(changeMessage);
-        window.MessageController.register(model.id, model);
-        conversation.trigger('newmessage', model);
-      });
-    }
-
-    // Capture profile key for each member in the group, if we don't have it yet
-    members.forEach(member => {
-      const contact = window.ConversationController.get(member.uuid);
-
-      if (member.profileKey && contact && !contact.get('profileKey')) {
-        contact.setProfileKey(member.profileKey);
-      }
-    });
-
-    await conversation.updateLastMessage();
+    await updateGroup({ conversation, receivedAt, sentAt, updates });
   } catch (error) {
     window.log.error(
       `maybeUpdateGroup/${logId}: Failed to update group:`,
@@ -372,6 +419,79 @@ export async function maybeUpdateGroup({
   }
 }
 
+async function updateGroup({
+  conversation,
+  receivedAt,
+  sentAt,
+  updates,
+}: {
+  conversation: ConversationModel;
+  receivedAt?: number;
+  sentAt?: number;
+  updates: UpdatesResultType;
+}): Promise<void> {
+  const { newAttributes, groupChangeMessages, members } = updates;
+
+  const startingRevision = conversation.get('revision');
+  const endingRevision = newAttributes.revision;
+
+  const isInitialDataFetch =
+    !isNumber(startingRevision) && isNumber(endingRevision);
+
+  // Ensure that all generated messages are ordered properly.
+  // Before the provided timestamp so update messages appear before the
+  //   initiating message, or after now().
+  let syntheticTimestamp = receivedAt
+    ? receivedAt - (groupChangeMessages.length + 1)
+    : Date.now();
+
+  conversation.set({
+    ...newAttributes,
+    // We force this conversation into the left pane if this is the first time we've
+    //   fetched data about it, and we were able to fetch its name. Nobody likes to see
+    //   Unknown Group in the left pane.
+    active_at:
+      isInitialDataFetch && newAttributes.name
+        ? syntheticTimestamp
+        : newAttributes.active_at,
+  });
+
+  // Save all synthetic messages describing group changes
+  const changeMessagesToSave = groupChangeMessages.map(changeMessage => {
+    // We do this to preserve the order of the timeline
+    syntheticTimestamp += 1;
+
+    return {
+      ...changeMessage,
+      conversationId: conversation.id,
+      received_at: syntheticTimestamp,
+      sent_at: sentAt,
+    };
+  });
+
+  if (changeMessagesToSave.length > 0) {
+    await window.Signal.Data.saveMessages(changeMessagesToSave, {
+      forceSave: true,
+    });
+    changeMessagesToSave.forEach(changeMessage => {
+      const model = new window.Whisper.Message(changeMessage);
+      window.MessageController.register(model.id, model);
+      conversation.trigger('newmessage', model);
+    });
+  }
+
+  // Capture profile key for each member in the group, if we don't have it yet
+  members.forEach(member => {
+    const contact = window.ConversationController.get(member.uuid);
+
+    if (member.profileKey && contact && !contact.get('profileKey')) {
+      contact.setProfileKey(member.profileKey);
+    }
+  });
+
+  // No need for convo.updateLastMessage(), 'newmessage' handler does that
+}
+
 function idForLogging(group: ConversationAttributesType) {
   return `groupv2(${group.groupId})`;
 }
@@ -396,12 +516,16 @@ async function getGroupUpdates({
   const currentRevision = group.revision;
   const isFirstFetch = !isNumber(group.revision);
 
+  const isInitialCreationMessage = isFirstFetch && newRevision === 0;
+  const isOneVersionUp =
+    isNumber(currentRevision) &&
+    isNumber(newRevision) &&
+    newRevision === currentRevision + 1;
+
   if (
     groupChangeBase64 &&
-    ((isFirstFetch && newRevision === 0) ||
-      (isNumber(newRevision) &&
-        isNumber(currentRevision) &&
-        newRevision === currentRevision + 1))
+    isNumber(newRevision) &&
+    (isInitialCreationMessage || isOneVersionUp)
   ) {
     window.log.info(`getGroupUpdates/${logId}: Processing just one change`);
     const groupChangeBuffer = base64ToArrayBuffer(groupChangeBase64);
@@ -700,9 +824,12 @@ async function integrateGroupChanges({
     for (let j = 0; j < jmax; j += 1) {
       const changeState = groupChanges[j];
 
-      const { groupChange } = changeState;
+      const { groupChange, groupState } = changeState;
 
-      if (!groupChange) {
+      if (!groupChange || !groupState) {
+        window.log.warn(
+          'integrateGroupChanges: item had neither groupState nor groupChange. Skipping.'
+        );
         // eslint-disable-next-line no-continue
         continue;
       }
@@ -717,6 +844,7 @@ async function integrateGroupChanges({
           group: attributes,
           newRevision,
           groupChange,
+          groupState,
         });
 
         attributes = newAttributes;
@@ -768,15 +896,19 @@ async function integrateGroupChanges({
 async function integrateGroupChange({
   group,
   groupChange,
+  groupState,
   newRevision,
 }: {
   group: ConversationAttributesType;
   groupChange: GroupChangeClass;
+  groupState?: GroupClass;
   newRevision: number;
 }): Promise<UpdatesResultType> {
   const logId = idForLogging(group);
   if (!group.secretParams) {
-    throw new Error('integrateGroupChange: Group was missing secretParams!');
+    throw new Error(
+      `integrateGroupChange/${logId}: Group was missing secretParams!`
+    );
   }
 
   const groupChangeActions = window.textsecure.protobuf.GroupChange.Actions.decode(
@@ -804,9 +936,48 @@ async function integrateGroupChange({
   );
   const sourceConversationId = sourceConversation.id;
 
+  const isFirstFetch = !isNumber(group.revision);
+  const isMoreThanOneVersionUp =
+    groupChangeActions.version &&
+    isNumber(group.revision) &&
+    groupChangeActions.version > group.revision + 1;
+
+  if (groupState && (isFirstFetch || isMoreThanOneVersionUp)) {
+    window.log.info(
+      `integrateGroupChange/${logId}: Applying full group state, from version ${group.revision} to ${groupState.version}`
+    );
+
+    const decryptedGroupState = decryptGroupState(
+      groupState,
+      group.secretParams,
+      logId
+    );
+
+    const newAttributes = await applyGroupState({
+      group,
+      groupState: decryptedGroupState,
+      sourceConversationId: isFirstFetch ? sourceConversationId : undefined,
+    });
+
+    return {
+      newAttributes,
+      groupChangeMessages: extractDiffs({
+        old: group,
+        current: newAttributes,
+        sourceConversationId: isFirstFetch ? sourceConversationId : undefined,
+      }),
+      members: getMembers(decryptedGroupState),
+    };
+  }
+
+  window.log.info(
+    `integrateGroupChange/${logId}: Applying group change actions, from version ${group.revision} to ${groupChangeActions.version}`
+  );
+
   const { newAttributes, newProfileKeys } = await applyGroupChange({
     group,
     actions: decryptedChangeActions,
+    sourceConversationId,
   });
   const groupChangeMessages = extractDiffs({
     old: group,
@@ -861,7 +1032,10 @@ export async function getCurrentGroupState({
     logId
   );
 
-  const newAttributes = await applyGroupState(group, decryptedGroupState);
+  const newAttributes = await applyGroupState({
+    group,
+    groupState: decryptedGroupState,
+  });
 
   return {
     newAttributes,
@@ -888,7 +1062,10 @@ function extractDiffs({
   const logId = idForLogging(old);
   const details: Array<GroupV2ChangeDetailType> = [];
   const ourConversationId = window.ConversationController.getOurConversationId();
+
   let areWeInGroup = false;
+  let areWeInvitedToGroup = false;
+  let whoInvitedUsUserId = null;
 
   if (
     current.accessControl &&
@@ -988,6 +1165,11 @@ function extractDiffs({
     const { conversationId } = currentPendingMember;
     const oldPendingMember = oldPendingMemberLookup[conversationId];
 
+    if (ourConversationId && conversationId === ourConversationId) {
+      areWeInvitedToGroup = true;
+      whoInvitedUsUserId = currentPendingMember.addedByUserId;
+    }
+
     if (!oldPendingMember) {
       lastPendingConversationId = conversationId;
       count += 1;
@@ -1049,16 +1231,50 @@ function extractDiffs({
   const sourceUuid = conversation ? conversation.get('uuid') : undefined;
 
   const firstUpdate = !isNumber(old.revision);
-  const firstEventSourceId = sourceConversationId || ourConversationId;
 
+  // Here we hardcode initial messages if this is our first time processing data this
+  //   group. Ideally we can collapse it down to just one of: 'you were added',
+  //   'you were invited', or 'you created.'
   if (firstUpdate && dropInitialJoinMessage) {
     message = undefined;
+  } else if (
+    firstUpdate &&
+    ourConversationId &&
+    sourceConversationId &&
+    sourceConversationId === ourConversationId
+  ) {
+    message = {
+      ...generateBasicMessage(),
+      type: 'group-v2-change',
+      groupV2Change: {
+        from: sourceConversationId,
+        details: [
+          {
+            type: 'create',
+          },
+        ],
+      },
+    };
+  } else if (firstUpdate && ourConversationId && areWeInvitedToGroup) {
+    message = {
+      ...generateBasicMessage(),
+      type: 'group-v2-change',
+      groupV2Change: {
+        from: whoInvitedUsUserId || sourceConversationId,
+        details: [
+          {
+            type: 'pending-add-one',
+            conversationId: ourConversationId,
+          },
+        ],
+      },
+    };
   } else if (firstUpdate && ourConversationId && areWeInGroup) {
     message = {
       ...generateBasicMessage(),
       type: 'group-v2-change',
       groupV2Change: {
-        from: firstEventSourceId,
+        from: sourceConversationId,
         details: [
           {
             type: 'member-add',
@@ -1067,6 +1283,19 @@ function extractDiffs({
         ],
       },
     };
+  } else if (firstUpdate) {
+    message = {
+      ...generateBasicMessage(),
+      type: 'group-v2-change',
+      groupV2Change: {
+        from: sourceConversationId,
+        details: [
+          {
+            type: 'create',
+          },
+        ],
+      },
+    };
   } else if (details.length > 0) {
     message = {
       ...generateBasicMessage(),
@@ -1132,18 +1361,22 @@ type GroupChangeResultType = {
 };
 
 async function applyGroupChange({
-  group,
   actions,
+  group,
+  sourceConversationId,
 }: {
-  sourceConversationId?: string;
-  group: ConversationAttributesType;
   actions: GroupChangeClass.Actions;
+  group: ConversationAttributesType;
+  sourceConversationId: string;
 }): Promise<GroupChangeResultType> {
   const logId = idForLogging(group);
+  const ourConversationId = window.ConversationController.getOurConversationId();
+
   const ACCESS_ENUM = window.textsecure.protobuf.AccessControl.AccessRequired;
   const MEMBER_ROLE_ENUM = window.textsecure.protobuf.Member.Role;
+
   const version = actions.version || 0;
-  const result = {
+  const result: ConversationAttributesType = {
     ...group,
   };
   const newProfileKeys: Array<GroupChangeMemberType> = [];
@@ -1198,6 +1431,15 @@ async function applyGroupChange({
       delete pendingMembers[conversation.id];
     }
 
+    // Capture who added us
+    if (
+      ourConversationId &&
+      sourceConversationId &&
+      conversation.id === ourConversationId
+    ) {
+      result.addedBy = sourceConversationId;
+    }
+
     if (added.profileKey) {
       newProfileKeys.push({
         profileKey: added.profileKey,
@@ -1438,7 +1680,6 @@ async function applyGroupChange({
     };
   }
 
-  const ourConversationId = window.ConversationController.getOurConversationId();
   if (ourConversationId) {
     result.left = !members[ourConversationId];
   }
@@ -1524,14 +1765,19 @@ async function applyNewAvatar(
 }
 /* eslint-enable no-param-reassign */
 
-async function applyGroupState(
-  group: ConversationAttributesType,
-  groupState: GroupClass
-): Promise<ConversationAttributesType> {
+async function applyGroupState({
+  group,
+  groupState,
+  sourceConversationId,
+}: {
+  group: ConversationAttributesType;
+  groupState: GroupClass;
+  sourceConversationId?: string;
+}): Promise<ConversationAttributesType> {
   const logId = idForLogging(group);
   const ACCESS_ENUM = window.textsecure.protobuf.AccessControl.AccessRequired;
   const version = groupState.version || 0;
-  const result = {
+  const result: ConversationAttributesType = {
     ...group,
   };
 
@@ -1589,6 +1835,16 @@ async function applyGroupState(
 
       if (ourConversationId && conversation.id === ourConversationId) {
         result.left = false;
+
+        // Capture who added us if we were previously not in group
+        if (
+          sourceConversationId &&
+          (result.membersV2 || []).every(
+            item => item.conversationId !== ourConversationId
+          )
+        ) {
+          result.addedBy = sourceConversationId;
+        }
       }
 
       if (
diff --git a/ts/model-types.d.ts b/ts/model-types.d.ts
index 6a1aeb17f..78cb02615 100644
--- a/ts/model-types.d.ts
+++ b/ts/model-types.d.ts
@@ -139,7 +139,7 @@ export type ConversationAttributesTypeType = 'private' | 'group';
 
 export type ConversationAttributesType = {
   accessKey: string | null;
-  addedBy: string;
+  addedBy?: string;
   capabilities: { uuid: string };
   color?: ColorType;
   discoveredUnregisteredAt: number;
@@ -155,8 +155,8 @@ export type ConversationAttributesType = {
   muteExpiresAt: number;
   pinIndex?: number;
   profileAvatar: WhatIsThis;
-  profileKeyCredential: unknown | null;
-  profileKeyVersion: string;
+  profileKeyCredential: string | null;
+  profileKeyVersion: string | null;
   quotedMessageId: string;
   sealedSender: unknown;
   sentMessageCount: number;
diff --git a/ts/models/conversations.ts b/ts/models/conversations.ts
index 6531045c3..7e5a889c4 100644
--- a/ts/models/conversations.ts
+++ b/ts/models/conversations.ts
@@ -7,7 +7,7 @@ import {
   ConversationAttributesType,
   VerificationOptions,
 } from '../model-types.d';
-import { CallbackResultType } from '../textsecure/SendMessage';
+import { CallbackResultType, GroupV2InfoType } from '../textsecure/SendMessage';
 import {
   ConversationType,
   ConversationTypeType,
@@ -25,6 +25,7 @@ import {
   stringFromBytes,
   verifyAccessKey,
 } from '../Crypto';
+import { GroupChangeClass } from '../textsecure.d';
 
 /* eslint-disable more/no-then */
 window.Whisper = window.Whisper || {};
@@ -107,11 +108,6 @@ export class ConversationModel extends window.Backbone.Model<
 
   messageCollection?: MessageModelCollectionType;
 
-  // backbone ensures this exists in initialize()
-  // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-  // @ts-ignore
-  messageRequestEnum: typeof window.textsecure.protobuf.SyncMessage.MessageRequestResponse.Type;
-
   ourNumber?: string;
 
   ourUuid?: string;
@@ -192,8 +188,6 @@ export class ConversationModel extends window.Backbone.Model<
     this.ourNumber = window.textsecure.storage.user.getNumber();
     this.ourUuid = window.textsecure.storage.user.getUuid();
     this.verifiedEnum = window.textsecure.storage.protocol.VerifiedStatus;
-    this.messageRequestEnum =
-      window.textsecure.protobuf.SyncMessage.MessageRequestResponse.Type;
 
     // This may be overridden by window.ConversationController.getOrCreate, and signify
     //   our first save to the database. Or first fetch from the database.
@@ -258,16 +252,334 @@ export class ConversationModel extends window.Backbone.Model<
   }
 
   isGroupV1(): boolean {
-    const groupID = this.get('groupId');
-    if (!groupID) {
+    const groupId = this.get('groupId');
+    if (!groupId) {
       return false;
     }
 
-    return fromEncodedBinaryToArrayBuffer(groupID).byteLength === 16;
+    return fromEncodedBinaryToArrayBuffer(groupId).byteLength === 16;
   }
 
   isGroupV2(): boolean {
-    return (this.get('groupVersion') || 0) === 2;
+    const groupId = this.get('groupId');
+    if (!groupId) {
+      return false;
+    }
+
+    const groupVersion = this.get('groupVersion') || 0;
+
+    return groupVersion === 2 && base64ToArrayBuffer(groupId).byteLength === 32;
+  }
+
+  isMemberPending(conversationId: string): boolean {
+    if (!this.isGroupV2()) {
+      throw new Error(
+        `isPendingMember: Called for non-GroupV2 conversation ${this.idForLogging()}`
+      );
+    }
+    const pendingMembersV2 = this.get('pendingMembersV2');
+
+    if (!pendingMembersV2 || !pendingMembersV2.length) {
+      return false;
+    }
+
+    return window._.any(
+      pendingMembersV2,
+      item => item.conversationId === conversationId
+    );
+  }
+
+  isMember(conversationId: string): boolean {
+    if (!this.isGroupV2()) {
+      throw new Error(
+        `isMember: Called for non-GroupV2 conversation ${this.idForLogging()}`
+      );
+    }
+    const membersV2 = this.get('membersV2');
+
+    if (!membersV2 || !membersV2.length) {
+      return false;
+    }
+
+    return window._.any(
+      membersV2,
+      item => item.conversationId === conversationId
+    );
+  }
+
+  async updateExpirationTimerInGroupV2(
+    seconds?: number
+  ): Promise<GroupChangeClass.Actions | undefined> {
+    const idLog = this.idForLogging();
+    const current = this.get('expireTimer');
+    const bothFalsey = Boolean(current) === false && Boolean(seconds) === false;
+
+    if (current === seconds || bothFalsey) {
+      window.log.warn(
+        `updateExpirationTimerInGroupV2/${idLog}: Requested timer ${seconds} is unchanged from existing ${current}.`
+      );
+      return undefined;
+    }
+
+    return window.Signal.Groups.buildDisappearingMessagesTimerChange({
+      expireTimer: seconds || 0,
+      group: this.attributes,
+    });
+  }
+
+  async promotePendingMember(
+    conversationId: string
+  ): Promise<GroupChangeClass.Actions | undefined> {
+    const idLog = this.idForLogging();
+
+    // This user's pending state may have changed in the time between the user's
+    //   button press and when we get here. It's especially important to check here
+    //   in conflict/retry cases.
+    if (!this.isMemberPending(conversationId)) {
+      window.log.warn(
+        `promotePendingMember/${idLog}: ${conversationId} is not a pending member of group. Returning early.`
+      );
+      return undefined;
+    }
+
+    const pendingMember = window.ConversationController.get(conversationId);
+    if (!pendingMember) {
+      throw new Error(
+        `promotePendingMember/${idLog}: No conversation found for conversation ${conversationId}`
+      );
+    }
+
+    // We need the user's profileKeyCredential, which requires a roundtrip with the
+    //   server, and most definitely their profileKey. A getProfiles() call will
+    //   ensure that we have as much as we can get with the data we have.
+    let profileKeyCredentialBase64 = pendingMember.get('profileKeyCredential');
+    if (!profileKeyCredentialBase64) {
+      await pendingMember.getProfiles();
+
+      profileKeyCredentialBase64 = pendingMember.get('profileKeyCredential');
+      if (!profileKeyCredentialBase64) {
+        throw new Error(
+          `promotePendingMember/${idLog}: No profileKeyCredential for conversation ${pendingMember.idForLogging()}`
+        );
+      }
+    }
+
+    return window.Signal.Groups.buildPromoteMemberChange({
+      group: this.attributes,
+      profileKeyCredentialBase64,
+      serverPublicParamsBase64: window.getServerPublicParams(),
+    });
+  }
+
+  async removePendingMember(
+    conversationId: string
+  ): Promise<GroupChangeClass.Actions | undefined> {
+    const idLog = this.idForLogging();
+
+    // This user's pending state may have changed in the time between the user's
+    //   button press and when we get here. It's especially important to check here
+    //   in conflict/retry cases.
+    if (!this.isMemberPending(conversationId)) {
+      window.log.warn(
+        `removePendingMember/${idLog}: ${conversationId} is not a pending member of group. Returning early.`
+      );
+      return undefined;
+    }
+
+    const pendingMember = window.ConversationController.get(conversationId);
+    if (!pendingMember) {
+      throw new Error(
+        `removePendingMember/${idLog}: No conversation found for conversation ${conversationId}`
+      );
+    }
+
+    const uuid = pendingMember.get('uuid');
+    if (!uuid) {
+      throw new Error(
+        `removePendingMember/${idLog}: Missing uuid for conversation ${pendingMember.idForLogging()}`
+      );
+    }
+
+    return window.Signal.Groups.buildDeletePendingMemberChange({
+      group: this.attributes,
+      uuid,
+    });
+  }
+
+  async removeMember(
+    conversationId: string
+  ): Promise<GroupChangeClass.Actions | undefined> {
+    const idLog = this.idForLogging();
+
+    // This user's pending state may have changed in the time between the user's
+    //   button press and when we get here. It's especially important to check here
+    //   in conflict/retry cases.
+    if (!this.isMember(conversationId)) {
+      window.log.warn(
+        `removeMember/${idLog}: ${conversationId} is not a pending member of group. Returning early.`
+      );
+      return undefined;
+    }
+
+    const member = window.ConversationController.get(conversationId);
+    if (!member) {
+      throw new Error(
+        `removeMember/${idLog}: No conversation found for conversation ${conversationId}`
+      );
+    }
+
+    const uuid = member.get('uuid');
+    if (!uuid) {
+      throw new Error(
+        `removeMember/${idLog}: Missing uuid for conversation ${member.idForLogging()}`
+      );
+    }
+
+    return window.Signal.Groups.buildDeleteMemberChange({
+      group: this.attributes,
+      uuid,
+    });
+  }
+
+  async modifyGroupV2({
+    name,
+    createGroupChange,
+  }: {
+    name: string;
+    createGroupChange: () => Promise<GroupChangeClass.Actions | undefined>;
+  }): Promise<void> {
+    const idLog = `${name}/${this.idForLogging()}`;
+
+    if (!this.isGroupV2()) {
+      throw new Error(
+        `modifyGroupV2/${idLog}: Called for non-GroupV2 conversation`
+      );
+    }
+
+    const ONE_MINUTE = 1000 * 60;
+    const startTime = Date.now();
+    const timeoutTime = startTime + ONE_MINUTE;
+
+    const MAX_ATTEMPTS = 5;
+
+    for (let attempt = 0; attempt < MAX_ATTEMPTS; attempt += 1) {
+      window.log.info(`modifyGroupV2/${idLog}: Starting attempt ${attempt}`);
+      try {
+        // eslint-disable-next-line no-await-in-loop
+        await window.waitForEmptyEventQueue();
+
+        window.log.info(`modifyGroupV2/${idLog}: Queuing attempt ${attempt}`);
+
+        // eslint-disable-next-line no-await-in-loop
+        await this.queueJob(async () => {
+          window.log.info(`modifyGroupV2/${idLog}: Running attempt ${attempt}`);
+
+          const actions = await createGroupChange();
+          if (!actions) {
+            window.log.warn(
+              `modifyGroupV2/${idLog}: No change actions. Returning early.`
+            );
+            return;
+          }
+
+          // The new revision has to be exactly one more than the current revision
+          //   or it won't upload properly, and it won't apply in maybeUpdateGroup
+          const currentRevision = this.get('revision');
+          const newRevision = actions.version;
+
+          if ((currentRevision || 0) + 1 !== newRevision) {
+            throw new Error(
+              `modifyGroupV2/${idLog}: Revision mismatch - ${currentRevision} to ${newRevision}.`
+            );
+          }
+
+          // Upload. If we don't have permission, the server will return an error here.
+          const groupChange = await window.Signal.Groups.uploadGroupChange({
+            actions,
+            group: this.attributes,
+            serverPublicParamsBase64: window.getServerPublicParams(),
+          });
+
+          const groupChangeBuffer = groupChange.toArrayBuffer();
+          const groupChangeBase64 = arrayBufferToBase64(groupChangeBuffer);
+
+          // Apply change locally, just like we would with an incoming change. This will
+          //   change conversation state and add change notifications to the timeline.
+          await window.Signal.Groups.maybeUpdateGroup({
+            conversation: this,
+            groupChangeBase64,
+            newRevision,
+          });
+
+          // Send message to notify group members (including pending members) of change
+          const profileKey = this.get('profileSharing')
+            ? window.storage.get('profileKey')
+            : undefined;
+
+          const sendOptions = this.getSendOptions();
+          const timestamp = Date.now();
+
+          const promise = this.wrapSend(
+            window.textsecure.messaging.sendMessageToGroup(
+              {
+                groupV2: this.getGroupV2Info({
+                  groupChange: groupChangeBuffer,
+                  includePendingMembers: true,
+                }),
+                timestamp,
+                profileKey,
+              },
+              sendOptions
+            )
+          );
+
+          // We don't save this message; we just use it to ensure that a sync message is
+          //   sent to our linked devices.
+          const m = new window.Whisper.Message(({
+            conversationId: this.id,
+            type: 'not-to-save',
+            sent_at: timestamp,
+            received_at: timestamp,
+            // TODO: DESKTOP-722
+            // this type does not fully implement the interface it is expected to
+          } as unknown) as MessageAttributesType);
+
+          // This is to ensure that the functions in send() and sendSyncMessage()
+          //   don't save anything to the database.
+          m.doNotSave = true;
+
+          await m.send(promise);
+        });
+
+        // If we've gotten here with no error, we exit!
+        window.log.info(
+          `modifyGroupV2/${idLog}: Update complete, with attempt ${attempt}!`
+        );
+        break;
+      } catch (error) {
+        if (error.code === 409 && Date.now() <= timeoutTime) {
+          window.log.info(
+            `modifyGroupV2/${idLog}: Conflict while updating. Trying again...`
+          );
+
+          // eslint-disable-next-line no-await-in-loop
+          await this.fetchLatestGroupV2Data();
+        } else if (error.code === 409) {
+          window.log.error(
+            `modifyGroupV2/${idLog}: Conflict while updating. Timed out; not retrying.`
+          );
+          // We don't wait here because we're breaking out of the loop immediately.
+          this.fetchLatestGroupV2Data();
+          throw error;
+        } else {
+          const errorString = error && error.stack ? error.stack : error;
+          window.log.error(
+            `modifyGroupV2/${idLog}: Error updating: ${errorString}`
+          );
+          throw error;
+        }
+      }
+    }
   }
 
   isEverUnregistered(): boolean {
@@ -522,7 +834,11 @@ export class ConversationModel extends window.Backbone.Model<
     window.Signal.Data.updateConversation(this.attributes);
   }
 
-  getGroupV2Info(groupChange?: ArrayBuffer): WhatIsThis {
+  getGroupV2Info(
+    options: { groupChange?: ArrayBuffer; includePendingMembers?: boolean } = {}
+  ): GroupV2InfoType | undefined {
+    const { groupChange, includePendingMembers } = options;
+
     if (this.isPrivate() || !this.isGroupV2()) {
       return undefined;
     }
@@ -533,7 +849,9 @@ export class ConversationModel extends window.Backbone.Model<
       ),
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       revision: this.get('revision')!,
-      members: this.getRecipients(),
+      members: this.getRecipients({
+        includePendingMembers,
+      }),
       groupChange,
     };
   }
@@ -854,7 +1172,11 @@ export class ConversationModel extends window.Backbone.Model<
    * This function is called when a message request is accepted in order to
    * handle sending read receipts and download any pending attachments.
    */
-  async handleReadAndDownloadAttachments(): Promise<void> {
+  async handleReadAndDownloadAttachments(
+    options: { isLocalAction?: boolean } = {}
+  ): Promise<void> {
+    const { isLocalAction } = options;
+
     let messages: MessageModelCollectionType | undefined;
     do {
       const first = messages ? messages.first() : undefined;
@@ -887,8 +1209,12 @@ export class ConversationModel extends window.Backbone.Model<
         timestamp: m.get('sent_at'),
         hasErrors: m.hasErrors(),
       }));
-      // eslint-disable-next-line no-await-in-loop
-      await this.sendReadReceiptsFor(receiptSpecs);
+
+      if (isLocalAction) {
+        // eslint-disable-next-line no-await-in-loop
+        await this.sendReadReceiptsFor(receiptSpecs);
+      }
+
       // eslint-disable-next-line no-await-in-loop
       await Promise.all(readMessages.map(m => m.queueAttachmentDownloads()));
     } while (messages.length > 0);
@@ -898,57 +1224,129 @@ export class ConversationModel extends window.Backbone.Model<
     response: number,
     { fromSync = false, viaStorageServiceSync = false } = {}
   ): Promise<void> {
+    const messageRequestEnum =
+      window.textsecure.protobuf.SyncMessage.MessageRequestResponse.Type;
+    const isLocalAction = !fromSync && !viaStorageServiceSync;
+    const ourConversationId = window.ConversationController.getOurConversationId();
+
     // Apply message request response locally
     this.set({
       messageRequestResponseType: response,
     });
     window.Signal.Data.updateConversation(this.attributes);
 
-    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    if (response === this.messageRequestEnum!.ACCEPT) {
+    if (response === messageRequestEnum.ACCEPT) {
       this.unblock({ viaStorageServiceSync });
       this.enableProfileSharing({ viaStorageServiceSync });
 
-      if (!fromSync) {
-        this.sendProfileKeyUpdate();
-        // Locally accepted
-        await this.handleReadAndDownloadAttachments();
+      await this.handleReadAndDownloadAttachments({ isLocalAction });
+
+      if (isLocalAction) {
+        if (this.isGroupV1() || this.isPrivate()) {
+          this.sendProfileKeyUpdate();
+        } else if (
+          ourConversationId &&
+          this.isGroupV2() &&
+          this.isMemberPending(ourConversationId)
+        ) {
+          await this.modifyGroupV2({
+            name: 'promotePendingMember',
+            createGroupChange: () =>
+              this.promotePendingMember(ourConversationId),
+          });
+        } else if (
+          ourConversationId &&
+          this.isGroupV2() &&
+          this.isMember(ourConversationId)
+        ) {
+          window.log.info(
+            'applyMessageRequestResponse/accept: Already a member of v2 group'
+          );
+        } else {
+          window.log.error(
+            'applyMessageRequestResponse/accept: Neither member nor pending member of v2 group'
+          );
+        }
       }
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    } else if (response === this.messageRequestEnum!.BLOCK) {
+    } else if (response === messageRequestEnum.BLOCK) {
       // Block locally, other devices should block upon receiving the sync message
       this.block({ viaStorageServiceSync });
       this.disableProfileSharing({ viaStorageServiceSync });
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    } else if (response === this.messageRequestEnum!.DELETE) {
+
+      if (isLocalAction) {
+        if (this.isGroupV1() || this.isPrivate()) {
+          await this.leaveGroup();
+        } else if (this.isGroupV2()) {
+          await this.leaveGroupV2();
+        }
+      }
+    } else if (response === messageRequestEnum.DELETE) {
+      this.disableProfileSharing({ viaStorageServiceSync });
+
       // Delete messages locally, other devices should delete upon receiving
       // the sync message
-      this.destroyMessages();
-      this.disableProfileSharing({ viaStorageServiceSync });
+      await this.destroyMessages();
       this.updateLastMessage();
-      if (!fromSync) {
+
+      if (isLocalAction) {
         this.trigger('unload', 'deleted from message request');
+
+        if (this.isGroupV1() || this.isPrivate()) {
+          await this.leaveGroup();
+        } else if (this.isGroupV2()) {
+          await this.leaveGroupV2();
+        }
       }
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    } else if (response === this.messageRequestEnum!.BLOCK_AND_DELETE) {
-      // Delete messages locally, other devices should delete upon receiving
-      // the sync message
-      this.destroyMessages();
-      this.disableProfileSharing({ viaStorageServiceSync });
-      this.updateLastMessage();
+    } else if (response === messageRequestEnum.BLOCK_AND_DELETE) {
       // Block locally, other devices should block upon receiving the sync message
       this.block({ viaStorageServiceSync });
-      // Leave group if this was a local action
-      if (!fromSync) {
-        // TODO: DESKTOP-721
-        // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-        // @ts-ignore
-        this.leaveGroup();
+      this.disableProfileSharing({ viaStorageServiceSync });
+
+      // Delete messages locally, other devices should delete upon receiving
+      // the sync message
+      await this.destroyMessages();
+      this.updateLastMessage();
+
+      if (isLocalAction) {
         this.trigger('unload', 'blocked and deleted from message request');
+
+        if (this.isGroupV1() || this.isPrivate()) {
+          await this.leaveGroup();
+        } else if (this.isGroupV2()) {
+          await this.leaveGroupV2();
+        }
       }
     }
   }
 
+  async leaveGroupV2(): Promise<void> {
+    const ourConversationId = window.ConversationController.getOurConversationId();
+
+    if (
+      ourConversationId &&
+      this.isGroupV2() &&
+      this.isMemberPending(ourConversationId)
+    ) {
+      await this.modifyGroupV2({
+        name: 'delete',
+        createGroupChange: () => this.removePendingMember(ourConversationId),
+      });
+    } else if (
+      ourConversationId &&
+      this.isGroupV2() &&
+      this.isMember(ourConversationId)
+    ) {
+      await this.modifyGroupV2({
+        name: 'delete',
+        createGroupChange: () => this.removeMember(ourConversationId),
+      });
+    } else {
+      window.log.error(
+        'leaveGroupV2: We were neither a member nor a pending member of the group'
+      );
+    }
+  }
+
   async syncMessageRequestResponse(response: number): Promise<void> {
     // Let this run, no await
     this.applyMessageRequestResponse(response);
@@ -1302,10 +1700,9 @@ export class ConversationModel extends window.Backbone.Model<
       return true;
     }
 
-    if (
-      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      this.getMessageRequestResponseType() === this.messageRequestEnum!.ACCEPT
-    ) {
+    const messageRequestEnum =
+      window.textsecure.protobuf.SyncMessage.MessageRequestResponse.Type;
+    if (this.getMessageRequestResponseType() === messageRequestEnum.ACCEPT) {
       return true;
     }
 
@@ -1611,15 +2008,24 @@ export class ConversationModel extends window.Backbone.Model<
     return this.jobQueue.add(taskWithTimeout);
   }
 
-  getMembers(): Array<WhatIsThis> {
+  getMembers(
+    options: { includePendingMembers?: boolean } = {}
+  ): Array<WhatIsThis> {
     if (this.isPrivate()) {
       return [this];
     }
 
     if (this.get('membersV2')) {
+      const { includePendingMembers } = options;
+      const members: Array<{ conversationId: string }> = includePendingMembers
+        ? [
+            ...(this.get('membersV2') || []),
+            ...(this.get('pendingMembersV2') || []),
+          ]
+        : this.get('membersV2') || [];
+
       return window._.compact(
-        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        this.get('membersV2')!.map(member => {
+        members.map(member => {
           const c = window.ConversationController.get(member.conversationId);
 
           // In groups we won't sent to contacts we believe are unregistered
@@ -1660,8 +2066,12 @@ export class ConversationModel extends window.Backbone.Model<
     return members.map(member => member.id);
   }
 
-  getRecipients(): Array<string> {
-    const members = this.getMembers();
+  getRecipients(
+    options: { includePendingMembers?: boolean } = {}
+  ): Array<string> {
+    const { includePendingMembers } = options;
+
+    const members = this.getMembers({ includePendingMembers });
 
     // Eliminate our
     return window._.compact(
@@ -1913,6 +2323,10 @@ export class ConversationModel extends window.Backbone.Model<
         );
       })();
 
+      // This is to ensure that the functions in send() and sendSyncMessage() don't save
+      //   anything to the database.
+      message.doNotSave = true;
+
       return message.send(this.wrapSend(promise));
     }).catch(error => {
       window.log.error(
@@ -2040,6 +2454,10 @@ export class ConversationModel extends window.Backbone.Model<
         );
       })();
 
+      // This is to ensure that the functions in send() and sendSyncMessage() don't save
+      //   anything to the database.
+      message.doNotSave = true;
+
       return message.send(this.wrapSend(promise));
     }).catch(error => {
       window.log.error('Error sending reaction', reaction, target, error);
@@ -2436,7 +2854,9 @@ export class ConversationModel extends window.Backbone.Model<
       return false;
     }
 
-    return Boolean(conv.get('name')) || conv.get('profileSharing');
+    return Boolean(
+      conv.isMe() || conv.get('name') || conv.get('profileSharing')
+    );
   }
 
   async updateLastMessage(): Promise<void> {
@@ -2500,74 +2920,6 @@ export class ConversationModel extends window.Backbone.Model<
     }
   }
 
-  async updateExpirationTimerInGroupV2(seconds?: number): Promise<void> {
-    // Make change on the server
-    const actions = window.Signal.Groups.buildDisappearingMessagesTimerChange({
-      expireTimer: seconds || 0,
-      group: this.attributes,
-    });
-    let signedGroupChange;
-    try {
-      signedGroupChange = await window.Signal.Groups.uploadGroupChange({
-        actions,
-        group: this.attributes,
-        serverPublicParamsBase64: window.getServerPublicParams(),
-      });
-    } catch (error) {
-      // Get latest GroupV2 data, since we ran into trouble updating it
-      this.fetchLatestGroupV2Data();
-      throw error;
-    }
-
-    // Update local conversation
-    this.set({
-      expireTimer: seconds || 0,
-      revision: actions.version,
-    });
-    window.Signal.Data.updateConversation(this.attributes);
-
-    // Create local notification
-    const timestamp = Date.now();
-    const id = window.getGuid();
-    const message = window.MessageController.register(
-      id,
-      new window.Whisper.Message(({
-        id,
-        conversationId: this.id,
-        sent_at: timestamp,
-        received_at: timestamp,
-        flags:
-          window.textsecure.protobuf.DataMessage.Flags.EXPIRATION_TIMER_UPDATE,
-        expirationTimerUpdate: {
-          expireTimer: seconds,
-          sourceUuid: this.ourUuid,
-        },
-        // TODO: DESKTOP-722
-      } as unknown) as typeof window.Whisper.MessageAttributesType)
-    );
-    await window.Signal.Data.saveMessage(message.attributes, {
-      Message: window.Whisper.Message,
-      forceSave: true,
-    });
-    this.trigger('newmessage', message);
-
-    // Send message to all group members
-    const profileKey = this.get('profileSharing')
-      ? window.storage.get('profileKey')
-      : undefined;
-    const sendOptions = this.getSendOptions();
-    const promise = window.textsecure.messaging.sendMessageToGroup(
-      {
-        groupV2: this.getGroupV2Info(signedGroupChange.toArrayBuffer()),
-        timestamp,
-        profileKey,
-      },
-      sendOptions
-    );
-
-    message.send(promise);
-  }
-
   async updateExpirationTimer(
     providedExpireTimer: number | undefined,
     providedSource: unknown,
@@ -2580,7 +2932,11 @@ export class ConversationModel extends window.Backbone.Model<
           'updateExpirationTimer: GroupV2 timers are not updated this way'
         );
       }
-      await this.updateExpirationTimerInGroupV2(providedExpireTimer);
+      await this.modifyGroupV2({
+        name: 'updateExpirationTimer',
+        createGroupChange: () =>
+          this.updateExpirationTimerInGroupV2(providedExpireTimer),
+      });
       return false;
     }
 
@@ -3018,11 +3374,15 @@ export class ConversationModel extends window.Backbone.Model<
       const profileKeyVersionHex = c.get('profileKeyVersion')!;
       const existingProfileKeyCredential = c.get('profileKeyCredential');
 
-      const weHaveVersion = Boolean(profileKey && uuid && profileKeyVersionHex);
       let profileKeyCredentialRequestHex;
       let profileCredentialRequestContext;
 
-      if (weHaveVersion && !existingProfileKeyCredential) {
+      if (
+        profileKey &&
+        uuid &&
+        profileKeyVersionHex &&
+        !existingProfileKeyCredential
+      ) {
         window.log.info('Generating request...');
         ({
           requestHex: profileKeyCredentialRequestHex,
diff --git a/ts/models/messages.ts b/ts/models/messages.ts
index 0c2bd5bfe..23a10778b 100644
--- a/ts/models/messages.ts
+++ b/ts/models/messages.ts
@@ -115,6 +115,10 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
 
   CURRENT_PROTOCOL_VERSION?: number;
 
+  // Set when sending some sync messages, so we get the functionality of
+  //   send(), without zombie messages going into the database.
+  doNotSave?: boolean;
+
   INITIAL_PROTOCOL_VERSION?: number;
 
   OUR_NUMBER?: string;
@@ -1715,7 +1719,7 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
 
     this.set({ errors });
 
-    if (!skipSave) {
+    if (!skipSave && !this.doNotSave) {
       await window.Signal.Data.saveMessage(this.attributes, {
         Message: window.Whisper.Message,
       });
@@ -2130,9 +2134,11 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
           unidentifiedDeliveries: result.unidentifiedDeliveries,
         });
 
-        await window.Signal.Data.saveMessage(this.attributes, {
-          Message: window.Whisper.Message,
-        });
+        if (!this.doNotSave) {
+          await window.Signal.Data.saveMessage(this.attributes, {
+            Message: window.Whisper.Message,
+          });
+        }
 
         this.trigger('sent', this);
         this.sendSyncMessage();
@@ -2315,9 +2321,16 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
           synced: true,
           dataMessage: null,
         });
-        return window.Signal.Data.saveMessage(this.attributes, {
+
+        // Return early, skip the save
+        if (this.doNotSave) {
+          return result;
+        }
+
+        await window.Signal.Data.saveMessage(this.attributes, {
           Message: window.Whisper.Message,
-        }).then(() => result);
+        });
+        return result;
       });
     };
 
diff --git a/ts/services/storageRecordOps.ts b/ts/services/storageRecordOps.ts
index 0756bd043..46ff5e075 100644
--- a/ts/services/storageRecordOps.ts
+++ b/ts/services/storageRecordOps.ts
@@ -237,18 +237,21 @@ function applyMessageRequestState(
   record: MessageRequestCapableRecord,
   conversation: ConversationModel
 ): void {
+  const messageRequestEnum =
+    window.textsecure.protobuf.SyncMessage.MessageRequestResponse.Type;
+
   if (record.blocked) {
-    conversation.applyMessageRequestResponse(
-      conversation.messageRequestEnum.BLOCK,
-      { fromSync: true, viaStorageServiceSync: true }
-    );
+    conversation.applyMessageRequestResponse(messageRequestEnum.BLOCK, {
+      fromSync: true,
+      viaStorageServiceSync: true,
+    });
   } else if (record.whitelisted) {
     // unblocking is also handled by this function which is why the next
     // condition is part of the else-if and not separate
-    conversation.applyMessageRequestResponse(
-      conversation.messageRequestEnum.ACCEPT,
-      { fromSync: true, viaStorageServiceSync: true }
-    );
+    conversation.applyMessageRequestResponse(messageRequestEnum.ACCEPT, {
+      fromSync: true,
+      viaStorageServiceSync: true,
+    });
   } else if (!record.blocked) {
     // if the condition above failed the state could still be blocked=false
     // in which case we should unblock the conversation
@@ -408,8 +411,9 @@ export async function mergeGroupV2Record(
 
   const now = Date.now();
   const conversationId = window.ConversationController.ensureGroup(groupId, {
-    // We want this conversation to show in the left pane when we first learn about it
-    active_at: now,
+    // Note: We don't set active_at, because we don't want the group to show until
+    //   we have information about it beyond these initial details.
+    //   see maybeUpdateGroup().
     timestamp: now,
     // Basic GroupV2 data
     groupVersion: 2,
diff --git a/ts/textsecure.d.ts b/ts/textsecure.d.ts
index 168f989a2..3db78d509 100644
--- a/ts/textsecure.d.ts
+++ b/ts/textsecure.d.ts
@@ -318,6 +318,7 @@ export declare class GroupChangeClass {
     data: ArrayBuffer | ByteBufferClass,
     encoding?: string
   ) => GroupChangeClass;
+  toArrayBuffer: () => ArrayBuffer;
 
   actions?: ProtoBinaryType;
   serverSignature?: ProtoBinaryType;
diff --git a/ts/textsecure/SendMessage.ts b/ts/textsecure/SendMessage.ts
index af7435e48..b4772e7a6 100644
--- a/ts/textsecure/SendMessage.ts
+++ b/ts/textsecure/SendMessage.ts
@@ -90,7 +90,7 @@ type QuoteAttachmentType = {
   attachmentPointer?: AttachmentPointerClass;
 };
 
-type GroupV2InfoType = {
+export type GroupV2InfoType = {
   groupChange?: ArrayBuffer;
   masterKey: ArrayBuffer;
   revision: number;
diff --git a/ts/util/zkgroup.ts b/ts/util/zkgroup.ts
index 46bd3c98d..5247c73b1 100644
--- a/ts/util/zkgroup.ts
+++ b/ts/util/zkgroup.ts
@@ -9,6 +9,7 @@ import {
   GroupSecretParams,
   ProfileKey,
   ProfileKeyCiphertext,
+  ProfileKeyCredential,
   ProfileKeyCredentialPresentation,
   ProfileKeyCredentialRequestContext,
   ProfileKeyCredentialResponse,
@@ -220,6 +221,29 @@ export function getAuthCredentialPresentation(
   return compatArrayToArrayBuffer(presentation.serialize());
 }
 
+export function createProfileKeyCredentialPresentation(
+  clientZkProfileCipher: ClientZkProfileOperations,
+  profileKeyCredentialBase64: string,
+  groupSecretParamsBase64: string
+): ArrayBuffer {
+  const profileKeyCredentialArray = base64ToCompatArray(
+    profileKeyCredentialBase64
+  );
+  const profileKeyCredential = new ProfileKeyCredential(
+    profileKeyCredentialArray
+  );
+  const secretParams = new GroupSecretParams(
+    base64ToCompatArray(groupSecretParamsBase64)
+  );
+
+  const presentation = clientZkProfileCipher.createProfileKeyCredentialPresentation(
+    secretParams,
+    profileKeyCredential
+  );
+
+  return compatArrayToArrayBuffer(presentation.serialize());
+}
+
 export function getClientZkAuthOperations(
   serverPublicParamsBase64: string
 ): ClientZkAuthOperations {
diff --git a/ts/views/conversation_view.ts b/ts/views/conversation_view.ts
index 527479186..d6d31e1c3 100644
--- a/ts/views/conversation_view.ts
+++ b/ts/views/conversation_view.ts
@@ -1,4 +1,9 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
+
+// Note: because this file is pulled in directly from background.html, we can't use any
+//   imports here aside from types. That means everything will have to be references via
+//   globals right on window.
+
 interface GetLinkPreviewResult {
   title: string;
   url: string;
@@ -249,10 +254,6 @@ Whisper.MaxAttachmentsToast = Whisper.ToastView.extend({
   template: window.i18n('maximumAttachments'),
 });
 
-Whisper.TimerConflictToast = Whisper.ToastView.extend({
-  template: window.i18n('GroupV2--timerConflict'),
-});
-
 Whisper.ConversationLoadingScreen = Whisper.View.extend({
   templateName: 'conversation-loading-screen',
   className: 'conversation-loading-screen',
@@ -592,26 +593,51 @@ Whisper.ConversationView = Whisper.View.extend({
       clearQuotedMessage: () => this.setQuoteMessage(null),
       micCellEl,
       attachmentListEl,
-      onAccept: this.model.syncMessageRequestResponse.bind(
-        this.model,
-        messageRequestEnum.ACCEPT
-      ),
-      onBlock: this.model.syncMessageRequestResponse.bind(
-        this.model,
-        messageRequestEnum.BLOCK
-      ),
-      onUnblock: this.model.syncMessageRequestResponse.bind(
-        this.model,
-        messageRequestEnum.ACCEPT
-      ),
-      onDelete: this.model.syncMessageRequestResponse.bind(
-        this.model,
-        messageRequestEnum.DELETE
-      ),
-      onBlockAndDelete: this.model.syncMessageRequestResponse.bind(
-        this.model,
-        messageRequestEnum.BLOCK_AND_DELETE
-      ),
+      onAccept: () => {
+        this.longRunningTaskWrapper({
+          name: 'onAccept',
+          task: this.model.syncMessageRequestResponse.bind(
+            this.model,
+            messageRequestEnum.ACCEPT
+          ),
+        });
+      },
+      onBlock: () => {
+        this.longRunningTaskWrapper({
+          name: 'onBlock',
+          task: this.model.syncMessageRequestResponse.bind(
+            this.model,
+            messageRequestEnum.BLOCK
+          ),
+        });
+      },
+      onUnblock: () => {
+        this.longRunningTaskWrapper({
+          name: 'onUnblock',
+          task: this.model.syncMessageRequestResponse.bind(
+            this.model,
+            messageRequestEnum.ACCEPT
+          ),
+        });
+      },
+      onDelete: () => {
+        this.longRunningTaskWrapper({
+          name: 'onDelete',
+          task: this.model.syncMessageRequestResponse.bind(
+            this.model,
+            messageRequestEnum.DELETE
+          ),
+        });
+      },
+      onBlockAndDelete: () => {
+        this.longRunningTaskWrapper({
+          name: 'onBlockAndDelete',
+          task: this.model.syncMessageRequestResponse.bind(
+            this.model,
+            messageRequestEnum.BLOCK_AND_DELETE
+          ),
+        });
+      },
     };
 
     this.compositionAreaView = new Whisper.ReactWrapperView({
@@ -626,6 +652,74 @@ Whisper.ConversationView = Whisper.View.extend({
     this.$('.composition-area-placeholder').append(this.compositionAreaView.el);
   },
 
+  async longRunningTaskWrapper({
+    name,
+    task,
+  }: {
+    name: string;
+    task: () => Promise<void>;
+  }): Promise<void> {
+    const idLog = `${name}/${this.model.idForLogging()}`;
+    const ONE_SECOND = 1000;
+
+    let progressView: any | undefined;
+    let progressTimeout: NodeJS.Timeout | undefined = setTimeout(() => {
+      window.log.info(`longRunningTaskWrapper/${idLog}: Creating spinner`);
+
+      // Note: this component uses a portal to render itself into the top-level DOM. No
+      //   need to attach it to the DOM here.
+      progressView = new Whisper.ReactWrapperView({
+        className: 'progress-modal-wrapper',
+        Component: window.Signal.Components.ProgressModal,
+      });
+    }, ONE_SECOND);
+
+    // Note: any task we put here needs to have its own safety valve; this function will
+    //   show a spinner until it's done
+    try {
+      window.log.info(`longRunningTaskWrapper/${idLog}: Starting task`);
+      await task();
+      window.log.info(
+        `longRunningTaskWrapper/${idLog}: Task completed successfully`
+      );
+
+      if (progressTimeout) {
+        clearTimeout(progressTimeout);
+        progressTimeout = undefined;
+      }
+      if (progressView) {
+        progressView.remove();
+        progressView = undefined;
+      }
+    } catch (error) {
+      window.log.error(
+        `longRunningTaskWrapper/${idLog}: Error!`,
+        error && error.stack ? error.stack : error
+      );
+
+      if (progressTimeout) {
+        clearTimeout(progressTimeout);
+        progressTimeout = undefined;
+      }
+      if (progressView) {
+        progressView.remove();
+        progressView = undefined;
+      }
+
+      window.log.info(`longRunningTaskWrapper/${idLog}: Showing error dialog`);
+
+      // Note: this component uses a portal to render itself into the top-level DOM. No
+      //   need to attach it to the DOM here.
+      const errorView = new Whisper.ReactWrapperView({
+        className: 'error-modal-wrapper',
+        Component: window.Signal.Components.ErrorModal,
+        props: {
+          onClose: () => errorView.remove(),
+        },
+      });
+    }
+  },
+
   setupTimeline() {
     const { id } = this.model;
 
@@ -2619,17 +2713,12 @@ Whisper.ConversationView = Whisper.View.extend({
   },
 
   async setDisappearingMessages(seconds: any) {
-    try {
-      if (seconds > 0) {
-        await this.model.updateExpirationTimer(seconds);
-      } else {
-        await this.model.updateExpirationTimer(null);
-      }
-    } catch (error) {
-      if (error.code === 409) {
-        this.showToast(Whisper.TimerConflictToast);
-      }
-    }
+    const valueToSet = seconds > 0 ? seconds : null;
+
+    await this.longRunningTaskWrapper({
+      name: 'updateExpirationTimer',
+      task: async () => this.model.updateExpirationTimer(valueToSet),
+    });
   },
 
   setMuteNotifications(ms: number) {
diff --git a/ts/window.d.ts b/ts/window.d.ts
index a9b1be25b..39a25f49d 100644
--- a/ts/window.d.ts
+++ b/ts/window.d.ts
@@ -16,8 +16,10 @@ import {
 import { ContactRecordIdentityState, TextSecureType } from './textsecure.d';
 import { WebAPIConnectType } from './textsecure/WebAPI';
 import { CallingClass } from './services/calling';
+import * as Groups from './groups';
 import * as Crypto from './Crypto';
 import * as RemoteConfig from './RemoteConfig';
+import * as zkgroup from './util/zkgroup';
 import { LocalizerType, BodyRangesType } from './types/Util';
 import { CallHistoryDetailsType } from './types/Calling';
 import { ColorType } from './types/Colors';
@@ -33,6 +35,8 @@ import { MessageModel } from './models/messages';
 import { ConversationModel } from './models/conversations';
 import { combineNames } from './util';
 import { BatcherType } from './util/batcher';
+import { ErrorModal } from './components/ErrorModal';
+import { ProgressModal } from './components/ProgressModal';
 
 export { Long } from 'long';
 
@@ -166,16 +170,7 @@ declare global {
       };
       Crypto: typeof Crypto;
       Data: typeof Data;
-      Groups: {
-        maybeUpdateGroup: (options: unknown) => Promise<void>;
-        waitThenMaybeUpdateGroup: (options: unknown) => Promise<void>;
-        uploadGroupChange: (
-          options: unknown
-        ) => Promise<{ toArrayBuffer: () => ArrayBuffer }>;
-        buildDisappearingMessagesTimerChange: (
-          options: unknown
-        ) => { version: number };
-      };
+      Groups: typeof Groups;
       Metadata: {
         SecretSessionCipher: typeof SecretSessionCipherClass;
         createCertificateValidator: (
@@ -383,23 +378,7 @@ declare global {
           del: unknown,
           bool: boolean
         ) => void;
-        zkgroup: {
-          generateProfileKeyCredentialRequest: (
-            clientZkProfileCipher: unknown,
-            uuid: string,
-            profileKey: unknown
-          ) => { requestHex: string; context: unknown };
-          getClientZkProfileOperations: (params: unknown) => unknown;
-          handleProfileKeyCredential: (
-            clientZkProfileCipher: unknown,
-            profileCredentialRequestContext: unknown,
-            credential: unknown
-          ) => unknown;
-          deriveProfileKeyVersion: (
-            profileKey: unknown,
-            uuid: string
-          ) => string;
-        };
+        zkgroup: typeof zkgroup;
         combineNames: typeof combineNames;
         migrateColor: (color: string) => ColorType;
         createBatcher: (options: WhatIsThis) => WhatIsThis;
@@ -429,20 +408,23 @@ declare global {
         renderChange: (change: unknown, things: unknown) => Array<string>;
       };
       Components: {
-        StagedLinkPreview: any;
-        Quote: any;
-        ContactDetail: any;
-        MessageDetail: any;
-        Lightbox: any;
-        MediaGallery: any;
-        CaptionEditor: any;
-        ConversationHeader: any;
         AttachmentList: any;
+        CaptionEditor: any;
+        ContactDetail: any;
+        ConversationHeader: any;
+        ErrorModal: typeof ErrorModal;
+        Lightbox: any;
+        LightboxGallery: any;
+        MediaGallery: any;
+        MessageDetail: any;
+        ProgressModal: typeof ProgressModal;
+        Quote: any;
+        StagedLinkPreview: any;
+
         getCallingNotificationText: (
           callHistoryDetails: unknown,
           i18n: unknown
         ) => string;
-        LightboxGallery: any;
       };
       OS: {
         isLinux: () => boolean;