diff --git a/lib/actions/thread-actions.js b/lib/actions/thread-actions.js
index de6f021bd..52b5bb35e 100644
--- a/lib/actions/thread-actions.js
+++ b/lib/actions/thread-actions.js
@@ -1,570 +1,575 @@
 // @flow
 
 import invariant from 'invariant';
 import * as React from 'react';
 import uuid from 'uuid';
 
 import genesis from '../facts/genesis.js';
 import { extractKeyserverIDFromID } from '../keyserver-conn/keyserver-call-utils.js';
 import { useKeyserverCall } from '../keyserver-conn/keyserver-call.js';
 import type { CallKeyserverEndpoint } from '../keyserver-conn/keyserver-conn-types.js';
 import {
   type OutboundDMOperationSpecification,
   dmOperationSpecificationTypes,
   getCreateThickRawThreadInfoInputFromThreadInfo,
 } from '../shared/dm-ops/dm-op-utils.js';
 import { useProcessAndSendDMOperation } from '../shared/dm-ops/process-dm-ops.js';
 import { permissionsAndAuthRelatedRequestTimeout } from '../shared/timeouts.js';
 import type {
   DMChangeThreadSettingsOperation,
   DMThreadSettingsChanges,
   DMJoinThreadOperation,
 } from '../types/dm-ops.js';
 import type {
   ThreadInfo,
   RawThreadInfo,
 } from '../types/minimally-encoded-thread-permissions-types.js';
 import { thickThreadTypes } from '../types/thread-types-enum.js';
 import type {
   ChangeThreadSettingsPayload,
   LeaveThreadPayload,
   UpdateThreadRequest,
   ClientNewThinThreadRequest,
   NewThreadResult,
   ClientThreadJoinRequest,
   ThreadJoinPayload,
   ThreadFetchMediaRequest,
   ThreadFetchMediaResult,
   RoleModificationRequest,
   RoleModificationPayload,
   RoleDeletionRequest,
   RoleDeletionPayload,
   UpdateThickThreadRequest,
 } from '../types/thread-types.js';
 import { values } from '../utils/objects.js';
 import { useSelector } from '../utils/redux-utils.js';
 
 export type DeleteThreadInput = {
   +threadID: string,
 };
 
 const deleteThreadActionTypes = Object.freeze({
   started: 'DELETE_THREAD_STARTED',
   success: 'DELETE_THREAD_SUCCESS',
   failed: 'DELETE_THREAD_FAILED',
 });
 
 const deleteThreadEndpointOptions = {
   timeout: permissionsAndAuthRelatedRequestTimeout,
 };
 
 const deleteThread =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: DeleteThreadInput) => Promise<LeaveThreadPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'delete_thread',
       requests,
       deleteThreadEndpointOptions,
     );
     const response = responses[keyserverID];
     return {
       updatesResult: response.updatesResult,
     };
   };
 
 function useDeleteThread(): (
   input: DeleteThreadInput,
 ) => Promise<LeaveThreadPayload> {
   return useKeyserverCall(deleteThread);
 }
 const changeThreadSettingsActionTypes = Object.freeze({
   started: 'CHANGE_THREAD_SETTINGS_STARTED',
   success: 'CHANGE_THREAD_SETTINGS_SUCCESS',
   failed: 'CHANGE_THREAD_SETTINGS_FAILED',
 });
 
 const changeThreadSettingsEndpointOptions = {
   timeout: permissionsAndAuthRelatedRequestTimeout,
 };
 
 const changeThreadSettings =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: UpdateThreadRequest) => Promise<ChangeThreadSettingsPayload>) =>
   async input => {
     invariant(
       Object.keys(input.changes).length > 0,
       'No changes provided to changeThreadSettings!',
     );
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'update_thread',
       requests,
       changeThreadSettingsEndpointOptions,
     );
     const response = responses[keyserverID];
     return {
       threadID: input.threadID,
       updatesResult: response.updatesResult,
       newMessageInfos: response.newMessageInfos,
     };
   };
 
 export type UseChangeThreadSettingsInput = $ReadOnly<
   | {
       ...UpdateThreadRequest,
       +thick: false,
     }
   | {
       ...UpdateThickThreadRequest,
       +thick: true,
       +threadInfo: ThreadInfo,
     },
 >;
 
 function useChangeThreadSettings(): (
   input: UseChangeThreadSettingsInput,
 ) => Promise<ChangeThreadSettingsPayload> {
   const processAndSendDMOperation = useProcessAndSendDMOperation();
   const viewerID = useSelector(
     state => state.currentUserInfo && state.currentUserInfo.id,
   );
 
   const keyserverCall = useKeyserverCall(changeThreadSettings);
 
   return React.useCallback(
     async (input: UseChangeThreadSettingsInput) => {
       if (!input.thick) {
         const { thick, ...rest } = input;
         return await keyserverCall({ ...rest });
       }
 
       invariant(viewerID, 'viewerID should be set');
 
       const changes: { ...DMThreadSettingsChanges } = {};
       if (input.changes.name) {
         changes.name = input.changes.name;
       }
       if (input.changes.description) {
         changes.description = input.changes.description;
       }
       if (input.changes.color) {
         changes.color = input.changes.color;
       }
       if (input.changes.avatar && input.changes.avatar.type === 'emoji') {
         changes.avatar = {
           type: 'emoji',
           emoji: input.changes.avatar.emoji,
           color: input.changes.avatar.color,
         };
       } else if (input.changes.avatar && input.changes.avatar.type === 'ens') {
         changes.avatar = { type: 'ens' };
+      } else if (
+        input.changes.avatar &&
+        input.changes.avatar.type === 'remove'
+      ) {
+        changes.avatar = null;
       }
       // To support `image` and `encrypted_image` avatars we first, need stop
       // sending multimedia metadata to keyserver.
       // ENG-8708
       const { threadInfo } = input;
       const op: DMChangeThreadSettingsOperation = {
         type: 'change_thread_settings',
         threadID: threadInfo.id,
         editorID: viewerID,
         time: Date.now(),
         changes,
         messageIDsPrefix: uuid.v4(),
       };
       const opSpecification: OutboundDMOperationSpecification = {
         type: dmOperationSpecificationTypes.OUTBOUND,
         op,
         recipients: {
           type: 'all_thread_members',
           threadID:
             threadInfo.type === thickThreadTypes.THICK_SIDEBAR &&
             threadInfo.parentThreadID
               ? threadInfo.parentThreadID
               : threadInfo.id,
         },
       };
 
       await processAndSendDMOperation(opSpecification);
       return ({
         threadID: threadInfo.id,
         updatesResult: { newUpdates: [] },
         newMessageInfos: [],
       }: ChangeThreadSettingsPayload);
     },
     [keyserverCall, processAndSendDMOperation, viewerID],
   );
 }
 
 export type RemoveUsersFromThreadInput = {
   +threadID: string,
   +memberIDs: $ReadOnlyArray<string>,
 };
 
 const removeUsersFromThreadActionTypes = Object.freeze({
   started: 'REMOVE_USERS_FROM_THREAD_STARTED',
   success: 'REMOVE_USERS_FROM_THREAD_SUCCESS',
   failed: 'REMOVE_USERS_FROM_THREAD_FAILED',
 });
 
 const removeMembersFromThreadEndpointOptions = {
   timeout: permissionsAndAuthRelatedRequestTimeout,
 };
 
 const removeUsersFromThread =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((
     input: RemoveUsersFromThreadInput,
   ) => Promise<ChangeThreadSettingsPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'remove_members',
       requests,
       removeMembersFromThreadEndpointOptions,
     );
     const response = responses[keyserverID];
     return {
       threadID: input.threadID,
       updatesResult: response.updatesResult,
       newMessageInfos: response.newMessageInfos,
     };
   };
 
 function useRemoveUsersFromThread(): (
   input: RemoveUsersFromThreadInput,
 ) => Promise<ChangeThreadSettingsPayload> {
   return useKeyserverCall(removeUsersFromThread);
 }
 
 export type ChangeThreadMemberRolesInput = {
   +threadID: string,
   +memberIDs: $ReadOnlyArray<string>,
   +newRole: string,
 };
 
 const changeThreadMemberRolesActionTypes = Object.freeze({
   started: 'CHANGE_THREAD_MEMBER_ROLES_STARTED',
   success: 'CHANGE_THREAD_MEMBER_ROLES_SUCCESS',
   failed: 'CHANGE_THREAD_MEMBER_ROLES_FAILED',
 });
 
 const changeThreadMemberRoleEndpointOptions = {
   timeout: permissionsAndAuthRelatedRequestTimeout,
 };
 
 const changeThreadMemberRoles =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((
     input: ChangeThreadMemberRolesInput,
   ) => Promise<ChangeThreadSettingsPayload>) =>
   async input => {
     const { threadID, memberIDs, newRole } = input;
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = {
       [keyserverID]: {
         threadID,
         memberIDs,
         role: newRole,
       },
     };
 
     const responses = await callKeyserverEndpoint(
       'update_role',
       requests,
       changeThreadMemberRoleEndpointOptions,
     );
     const response = responses[keyserverID];
     return {
       threadID,
       updatesResult: response.updatesResult,
       newMessageInfos: response.newMessageInfos,
     };
   };
 
 function useChangeThreadMemberRoles(): (
   input: ChangeThreadMemberRolesInput,
 ) => Promise<ChangeThreadSettingsPayload> {
   return useKeyserverCall(changeThreadMemberRoles);
 }
 
 const newThreadActionTypes = Object.freeze({
   started: 'NEW_THREAD_STARTED',
   success: 'NEW_THREAD_SUCCESS',
   failed: 'NEW_THREAD_FAILED',
 });
 const newThinThread =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: ClientNewThinThreadRequest) => Promise<NewThreadResult>) =>
   async input => {
     const parentThreadID = input.parentThreadID ?? genesis().id;
     const keyserverID = extractKeyserverIDFromID(parentThreadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint('create_thread', requests);
     const response = responses[keyserverID];
 
     return {
       newThreadID: response.newThreadID,
       updatesResult: response.updatesResult,
       newMessageInfos: response.newMessageInfos,
       userInfos: response.userInfos,
     };
   };
 
 function useNewThinThread(): (
   input: ClientNewThinThreadRequest,
 ) => Promise<NewThreadResult> {
   return useKeyserverCall(newThinThread);
 }
 
 const joinThreadActionTypes = Object.freeze({
   started: 'JOIN_THREAD_STARTED',
   success: 'JOIN_THREAD_SUCCESS',
   failed: 'JOIN_THREAD_FAILED',
 });
 const joinThreadOptions = {
   timeout: permissionsAndAuthRelatedRequestTimeout,
 };
 const joinThread =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: ClientThreadJoinRequest) => Promise<ThreadJoinPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'join_thread',
       requests,
       joinThreadOptions,
     );
     const response = responses[keyserverID];
     const userInfos = values(response.userInfos);
     return {
       updatesResult: response.updatesResult,
       rawMessageInfos: response.rawMessageInfos,
       truncationStatuses: response.truncationStatuses,
       userInfos,
       keyserverID,
     };
   };
 
 export type UseJoinThreadInput = $ReadOnly<
   | {
       +thick: false,
       ...ClientThreadJoinRequest,
     }
   | {
       +thick: true,
       +rawThreadInfo: RawThreadInfo,
     },
 >;
 
 function useJoinThread(): (
   input: UseJoinThreadInput,
 ) => Promise<ThreadJoinPayload> {
   const processAndSendDMOperation = useProcessAndSendDMOperation();
   const viewerID = useSelector(
     state => state.currentUserInfo && state.currentUserInfo.id,
   );
   const keyserverCall = useKeyserverCall(joinThread);
   return React.useCallback(
     async (input: UseJoinThreadInput) => {
       if (!input.thick) {
         const { thick, ...rest } = input;
         return await keyserverCall({ ...rest });
       }
 
       const { rawThreadInfo } = input;
 
       invariant(viewerID, 'viewerID should be set');
       invariant(rawThreadInfo.thick, 'thread must be thick');
 
       const existingThreadDetails =
         getCreateThickRawThreadInfoInputFromThreadInfo(rawThreadInfo);
 
       const op: DMJoinThreadOperation = {
         type: 'join_thread',
         joinerID: viewerID,
         time: Date.now(),
         messageID: uuid.v4(),
         existingThreadDetails,
       };
 
       const opSpecification: OutboundDMOperationSpecification = {
         type: dmOperationSpecificationTypes.OUTBOUND,
         op,
         recipients: {
           type: 'all_thread_members',
           threadID:
             rawThreadInfo.type === thickThreadTypes.THICK_SIDEBAR &&
             rawThreadInfo.parentThreadID
               ? rawThreadInfo.parentThreadID
               : rawThreadInfo.id,
         },
       };
 
       await processAndSendDMOperation(opSpecification);
       return ({
         updatesResult: { newUpdates: [] },
         rawMessageInfos: [],
         truncationStatuses: {},
         userInfos: [],
       }: ThreadJoinPayload);
     },
     [keyserverCall, processAndSendDMOperation, viewerID],
   );
 }
 
 export type LeaveThreadInput = {
   +threadID: string,
 };
 const leaveThreadActionTypes = Object.freeze({
   started: 'LEAVE_THREAD_STARTED',
   success: 'LEAVE_THREAD_SUCCESS',
   failed: 'LEAVE_THREAD_FAILED',
 });
 const leaveThreadEndpointOptions = {
   timeout: permissionsAndAuthRelatedRequestTimeout,
 };
 const leaveThread =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: LeaveThreadInput) => Promise<LeaveThreadPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'leave_thread',
       requests,
       leaveThreadEndpointOptions,
     );
     const response = responses[keyserverID];
     return {
       updatesResult: response.updatesResult,
     };
   };
 
 function useLeaveThread(): (
   input: LeaveThreadInput,
 ) => Promise<LeaveThreadPayload> {
   return useKeyserverCall(leaveThread);
 }
 
 const fetchThreadMedia =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: ThreadFetchMediaRequest) => Promise<ThreadFetchMediaResult>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'fetch_thread_media',
       requests,
     );
     const response = responses[keyserverID];
     return { media: response.media };
   };
 
 function useFetchThreadMedia(): (
   input: ThreadFetchMediaRequest,
 ) => Promise<ThreadFetchMediaResult> {
   return useKeyserverCall(fetchThreadMedia);
 }
 
 const modifyCommunityRoleActionTypes = Object.freeze({
   started: 'MODIFY_COMMUNITY_ROLE_STARTED',
   success: 'MODIFY_COMMUNITY_ROLE_SUCCESS',
   failed: 'MODIFY_COMMUNITY_ROLE_FAILED',
 });
 const modifyCommunityRole =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: RoleModificationRequest) => Promise<RoleModificationPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.community);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'modify_community_role',
       requests,
     );
     const response = responses[keyserverID];
     return {
       threadInfo: response.threadInfo,
       updatesResult: response.updatesResult,
     };
   };
 
 function useModifyCommunityRole(): (
   input: RoleModificationRequest,
 ) => Promise<RoleModificationPayload> {
   return useKeyserverCall(modifyCommunityRole);
 }
 
 const deleteCommunityRoleActionTypes = Object.freeze({
   started: 'DELETE_COMMUNITY_ROLE_STARTED',
   success: 'DELETE_COMMUNITY_ROLE_SUCCESS',
   failed: 'DELETE_COMMUNITY_ROLE_FAILED',
 });
 const deleteCommunityRole =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: RoleDeletionRequest) => Promise<RoleDeletionPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.community);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'delete_community_role',
       requests,
     );
     const response = responses[keyserverID];
     return {
       threadInfo: response.threadInfo,
       updatesResult: response.updatesResult,
     };
   };
 
 function useDeleteCommunityRole(): (
   input: RoleDeletionRequest,
 ) => Promise<RoleDeletionPayload> {
   return useKeyserverCall(deleteCommunityRole);
 }
 
 export {
   deleteThreadActionTypes,
   useDeleteThread,
   changeThreadSettingsActionTypes,
   useChangeThreadSettings,
   removeUsersFromThreadActionTypes,
   useRemoveUsersFromThread,
   changeThreadMemberRolesActionTypes,
   useChangeThreadMemberRoles,
   newThreadActionTypes,
   useNewThinThread,
   joinThreadActionTypes,
   useJoinThread,
   leaveThreadActionTypes,
   useLeaveThread,
   useFetchThreadMedia,
   modifyCommunityRoleActionTypes,
   useModifyCommunityRole,
   deleteCommunityRoleActionTypes,
   useDeleteCommunityRole,
 };
diff --git a/lib/shared/dm-ops/change-thread-settings-spec.js b/lib/shared/dm-ops/change-thread-settings-spec.js
index 872718e50..6d27a9179 100644
--- a/lib/shared/dm-ops/change-thread-settings-spec.js
+++ b/lib/shared/dm-ops/change-thread-settings-spec.js
@@ -1,174 +1,183 @@
 // @flow
 
 import invariant from 'invariant';
 import uuid from 'uuid';
 
 import type {
   DMOperationSpec,
   ProcessDMOperationUtilities,
 } from './dm-op-spec.js';
 import type {
   DMChangeThreadSettingsOperation,
   DMThreadSettingsChanges,
 } from '../../types/dm-ops.js';
 import type { MessageData, RawMessageInfo } from '../../types/message-types';
 import { messageTypes } from '../../types/message-types-enum.js';
 import type { ChangeSettingsMessageData } from '../../types/messages/change-settings.js';
 import type {
   RawThreadInfo,
   ThickRawThreadInfo,
 } from '../../types/minimally-encoded-thread-permissions-types.js';
 import { updateTypes } from '../../types/update-types-enum.js';
 import type { ClientUpdateInfo } from '../../types/update-types.js';
 import { values } from '../../utils/objects.js';
 import { rawMessageInfoFromMessageData } from '../message-utils.js';
 
 function getThreadIDFromChangeThreadSettingsDMOp(
   dmOperation: DMChangeThreadSettingsOperation,
 ): string {
   return dmOperation.type === 'change_thread_settings'
     ? dmOperation.threadID
     : dmOperation.existingThreadDetails.threadID;
 }
 
 function createChangeSettingsMessageDatasAndUpdate(
   dmOperation: DMChangeThreadSettingsOperation,
 ): {
   +fieldNameToMessageData: { +[fieldName: string]: ChangeSettingsMessageData },
   +threadInfoUpdate: DMThreadSettingsChanges,
 } {
   const { changes, editorID, time } = dmOperation;
   const { name, description, color, avatar } = changes;
   const threadID = getThreadIDFromChangeThreadSettingsDMOp(dmOperation);
 
   const threadInfoUpdate: { ...DMThreadSettingsChanges } = {};
 
   if (name !== undefined && name !== null) {
     threadInfoUpdate.name = name;
   }
 
   if (description !== undefined && description !== null) {
     threadInfoUpdate.description = description;
   }
 
   if (color) {
     threadInfoUpdate.color = color;
   }
 
-  if (avatar) {
+  if (avatar || avatar === null) {
     threadInfoUpdate.avatar = avatar;
   }
 
   const fieldNameToMessageData: {
     [fieldName: string]: ChangeSettingsMessageData,
   } = {};
 
   const { avatar: avatarObject, ...rest } = threadInfoUpdate;
-  const normalizedThreadInfoUpdate = avatarObject
-    ? { ...rest, avatar: JSON.stringify(avatarObject) }
-    : { ...rest };
+  let normalizedThreadInfoUpdate;
+  if (avatarObject) {
+    normalizedThreadInfoUpdate = {
+      ...rest,
+      avatar: JSON.stringify(avatarObject),
+    };
+  } else if (avatarObject === null) {
+    // clear thread avatar
+    normalizedThreadInfoUpdate = { ...rest, avatar: '' };
+  } else {
+    normalizedThreadInfoUpdate = { ...rest };
+  }
 
   for (const fieldName in normalizedThreadInfoUpdate) {
     const value = normalizedThreadInfoUpdate[fieldName];
     fieldNameToMessageData[fieldName] = {
       type: messageTypes.CHANGE_SETTINGS,
       threadID,
       creatorID: editorID,
       time,
       field: fieldName,
       value: value,
     };
   }
 
   return { fieldNameToMessageData, threadInfoUpdate };
 }
 
 const changeThreadSettingsSpec: DMOperationSpec<DMChangeThreadSettingsOperation> =
   Object.freeze({
     notificationsCreationData: async (
       dmOperation: DMChangeThreadSettingsOperation,
     ) => {
       const messageDatas: Array<MessageData> = [];
 
       const { fieldNameToMessageData } =
         createChangeSettingsMessageDatasAndUpdate(dmOperation);
       messageDatas.push(...values(fieldNameToMessageData));
       return { messageDatas };
     },
     processDMOperation: async (
       dmOperation: DMChangeThreadSettingsOperation,
       viewerID: string,
       utilities: ProcessDMOperationUtilities,
     ) => {
       const { time, messageIDsPrefix } = dmOperation;
       const threadID = getThreadIDFromChangeThreadSettingsDMOp(dmOperation);
 
       const threadInfo: ?RawThreadInfo = utilities.threadInfos[threadID];
       const updateInfos: Array<ClientUpdateInfo> = [];
       const rawMessageInfos: Array<RawMessageInfo> = [];
 
       const { fieldNameToMessageData, threadInfoUpdate } =
         createChangeSettingsMessageDatasAndUpdate(dmOperation);
 
       const fieldNameToMessageDataPairs = Object.entries(
         fieldNameToMessageData,
       );
       rawMessageInfos.push(
         ...fieldNameToMessageDataPairs.map(([fieldName, messageData]) =>
           rawMessageInfoFromMessageData(
             messageData,
             `${messageIDsPrefix}/${fieldName}`,
           ),
         ),
       );
 
       invariant(threadInfo?.thick, 'Thread should be thick');
       let threadInfoToUpdate: ThickRawThreadInfo = threadInfo;
       for (const fieldName in threadInfoUpdate) {
         const timestamp = threadInfoToUpdate.timestamps[fieldName];
         if (timestamp < time) {
           threadInfoToUpdate = {
             ...threadInfoToUpdate,
             [fieldName]: threadInfoUpdate[fieldName],
             timestamps: {
               ...threadInfoToUpdate.timestamps,
               [fieldName]: time,
             },
           };
         }
       }
 
       if (fieldNameToMessageDataPairs.length > 0) {
         updateInfos.push({
           type: updateTypes.UPDATE_THREAD,
           id: uuid.v4(),
           time,
           threadInfo: threadInfoToUpdate,
         });
       }
 
       return {
         rawMessageInfos,
         updateInfos,
       };
     },
     canBeProcessed(
       dmOperation: DMChangeThreadSettingsOperation,
       viewerID: string,
       utilities: ProcessDMOperationUtilities,
     ) {
       if (utilities.threadInfos[dmOperation.threadID]) {
         return { isProcessingPossible: true };
       }
       return {
         isProcessingPossible: false,
         reason: {
           type: 'missing_thread',
           threadID: dmOperation.threadID,
         },
       };
     },
     supportsAutoRetry: true,
   });
 
 export { changeThreadSettingsSpec, createChangeSettingsMessageDatasAndUpdate };
diff --git a/lib/types/dm-ops.js b/lib/types/dm-ops.js
index 8296fd758..d9c034b86 100644
--- a/lib/types/dm-ops.js
+++ b/lib/types/dm-ops.js
@@ -1,438 +1,438 @@
 // @flow
 
 import t, { type TInterface, type TUnion } from 'tcomb';
 
 import { clientAvatarValidator, type ClientAvatar } from './avatar-types.js';
 import type { RawMessageInfo } from './message-types.js';
 import type { NotificationsCreationData } from './notif-types.js';
 import type { OutboundP2PMessage } from './sqlite-types.js';
 import {
   type ThreadSubscription,
   threadSubscriptionValidator,
 } from './subscription-types.js';
 import {
   type NonSidebarThickThreadType,
   nonSidebarThickThreadTypes,
   type ThickThreadType,
   thickThreadTypeValidator,
 } from './thread-types-enum.js';
 import {
   threadTimestampsValidator,
   type ThreadTimestamps,
 } from './thread-types.js';
 import type { ClientUpdateInfo } from './update-types.js';
 import { values } from '../utils/objects.js';
 import { tColor, tShape, tString, tUserID } from '../utils/validation-utils.js';
 
 export const dmOperationTypes = Object.freeze({
   CREATE_THREAD: 'create_thread',
   CREATE_SIDEBAR: 'create_sidebar',
   SEND_TEXT_MESSAGE: 'send_text_message',
   SEND_REACTION_MESSAGE: 'send_reaction_message',
   SEND_EDIT_MESSAGE: 'send_edit_message',
   ADD_MEMBERS: 'add_members',
   ADD_VIEWER_TO_THREAD_MEMBERS: 'add_viewer_to_thread_members',
   JOIN_THREAD: 'join_thread',
   LEAVE_THREAD: 'leave_thread',
   REMOVE_MEMBERS: 'remove_members',
   CHANGE_THREAD_SETTINGS: 'change_thread_settings',
   CHANGE_THREAD_SUBSCRIPTION: 'change_thread_subscription',
   CHANGE_THREAD_READ_STATUS: 'change_thread_read_status',
 });
 export type DMOperationType = $Values<typeof dmOperationTypes>;
 
 type MemberIDWithSubscription = {
   +id: string,
   +subscription: ThreadSubscription,
 };
 export const memberIDWithSubscriptionValidator: TInterface<MemberIDWithSubscription> =
   tShape<MemberIDWithSubscription>({
     id: tUserID,
     subscription: threadSubscriptionValidator,
   });
 
 export type CreateThickRawThreadInfoInput = {
   +threadID: string,
   +threadType: ThickThreadType,
   +creationTime: number,
   +parentThreadID?: ?string,
   +allMemberIDsWithSubscriptions: $ReadOnlyArray<MemberIDWithSubscription>,
   +roleID: string,
   +unread: boolean,
   +timestamps: ThreadTimestamps,
   +name?: ?string,
   +avatar?: ?ClientAvatar,
   +description?: ?string,
   +color?: ?string,
   +containingThreadID?: ?string,
   +sourceMessageID?: ?string,
   +repliesCount?: ?number,
   +pinnedCount?: ?number,
 };
 export const createThickRawThreadInfoInputValidator: TInterface<CreateThickRawThreadInfoInput> =
   tShape<CreateThickRawThreadInfoInput>({
     threadID: t.String,
     threadType: thickThreadTypeValidator,
     creationTime: t.Number,
     parentThreadID: t.maybe(t.String),
     allMemberIDsWithSubscriptions: t.list(memberIDWithSubscriptionValidator),
     roleID: t.String,
     unread: t.Boolean,
     timestamps: threadTimestampsValidator,
     name: t.maybe(t.String),
     avatar: t.maybe(clientAvatarValidator),
     description: t.maybe(t.String),
     color: t.maybe(t.String),
     containingThreadID: t.maybe(t.String),
     sourceMessageID: t.maybe(t.String),
     repliesCount: t.maybe(t.Number),
     pinnedCount: t.maybe(t.Number),
   });
 
 export type DMCreateThreadOperation = {
   +type: 'create_thread',
   +threadID: string,
   +creatorID: string,
   +time: number,
   +threadType: NonSidebarThickThreadType,
   +memberIDs: $ReadOnlyArray<string>,
   +roleID: string,
   +newMessageID: string,
 };
 export const dmCreateThreadOperationValidator: TInterface<DMCreateThreadOperation> =
   tShape<DMCreateThreadOperation>({
     type: tString(dmOperationTypes.CREATE_THREAD),
     threadID: t.String,
     creatorID: tUserID,
     time: t.Number,
     threadType: t.enums.of(values(nonSidebarThickThreadTypes)),
     memberIDs: t.list(tUserID),
     roleID: t.String,
     newMessageID: t.String,
   });
 
 export type DMCreateSidebarOperation = {
   +type: 'create_sidebar',
   +threadID: string,
   +creatorID: string,
   +time: number,
   +parentThreadID: string,
   +memberIDs: $ReadOnlyArray<string>,
   +sourceMessageID: string,
   +roleID: string,
   +newSidebarSourceMessageID: string,
   +newCreateSidebarMessageID: string,
 };
 export const dmCreateSidebarOperationValidator: TInterface<DMCreateSidebarOperation> =
   tShape<DMCreateSidebarOperation>({
     type: tString(dmOperationTypes.CREATE_SIDEBAR),
     threadID: t.String,
     creatorID: tUserID,
     time: t.Number,
     parentThreadID: t.String,
     memberIDs: t.list(tUserID),
     sourceMessageID: t.String,
     roleID: t.String,
     newSidebarSourceMessageID: t.String,
     newCreateSidebarMessageID: t.String,
   });
 
 export type DMSendTextMessageOperation = {
   +type: 'send_text_message',
   +threadID: string,
   +creatorID: string,
   +time: number,
   +messageID: string,
   +text: string,
 };
 export const dmSendTextMessageOperationValidator: TInterface<DMSendTextMessageOperation> =
   tShape<DMSendTextMessageOperation>({
     type: tString(dmOperationTypes.SEND_TEXT_MESSAGE),
     threadID: t.String,
     creatorID: tUserID,
     time: t.Number,
     messageID: t.String,
     text: t.String,
   });
 
 export type DMSendReactionMessageOperation = {
   +type: 'send_reaction_message',
   +threadID: string,
   +creatorID: string,
   +time: number,
   +messageID: string,
   +targetMessageID: string,
   +reaction: string,
   +action: 'add_reaction' | 'remove_reaction',
 };
 export const dmSendReactionMessageOperationValidator: TInterface<DMSendReactionMessageOperation> =
   tShape<DMSendReactionMessageOperation>({
     type: tString(dmOperationTypes.SEND_REACTION_MESSAGE),
     threadID: t.String,
     creatorID: tUserID,
     time: t.Number,
     messageID: t.String,
     targetMessageID: t.String,
     reaction: t.String,
     action: t.enums.of(['add_reaction', 'remove_reaction']),
   });
 
 export type DMSendEditMessageOperation = {
   +type: 'send_edit_message',
   +threadID: string,
   +creatorID: string,
   +time: number,
   +messageID: string,
   +targetMessageID: string,
   +text: string,
 };
 export const dmSendEditMessageOperationValidator: TInterface<DMSendEditMessageOperation> =
   tShape<DMSendEditMessageOperation>({
     type: tString(dmOperationTypes.SEND_EDIT_MESSAGE),
     threadID: t.String,
     creatorID: tUserID,
     time: t.Number,
     messageID: t.String,
     targetMessageID: t.String,
     text: t.String,
   });
 
 type DMAddMembersBase = {
   +editorID: string,
   +time: number,
   +addedUserIDs: $ReadOnlyArray<string>,
 };
 const dmAddMembersBaseValidatorShape = {
   editorID: tUserID,
   time: t.Number,
   addedUserIDs: t.list(tUserID),
 };
 
 export type DMAddMembersOperation = $ReadOnly<{
   +type: 'add_members',
   +threadID: string,
   +messageID: string,
   ...DMAddMembersBase,
 }>;
 export const dmAddMembersOperationValidator: TInterface<DMAddMembersOperation> =
   tShape<DMAddMembersOperation>({
     type: tString(dmOperationTypes.ADD_MEMBERS),
     threadID: t.String,
     messageID: t.String,
     ...dmAddMembersBaseValidatorShape,
   });
 
 export type DMAddViewerToThreadMembersOperation = $ReadOnly<{
   +type: 'add_viewer_to_thread_members',
   +messageID: ?string,
   +existingThreadDetails: CreateThickRawThreadInfoInput,
   ...DMAddMembersBase,
 }>;
 export const dmAddViewerToThreadMembersValidator: TInterface<DMAddViewerToThreadMembersOperation> =
   tShape<DMAddViewerToThreadMembersOperation>({
     type: tString(dmOperationTypes.ADD_VIEWER_TO_THREAD_MEMBERS),
     messageID: t.maybe(t.String),
     existingThreadDetails: createThickRawThreadInfoInputValidator,
     ...dmAddMembersBaseValidatorShape,
   });
 
 export type DMJoinThreadOperation = {
   +type: 'join_thread',
   +joinerID: string,
   +time: number,
   +messageID: string,
   +existingThreadDetails: CreateThickRawThreadInfoInput,
 };
 export const dmJoinThreadOperationValidator: TInterface<DMJoinThreadOperation> =
   tShape<DMJoinThreadOperation>({
     type: tString(dmOperationTypes.JOIN_THREAD),
     joinerID: tUserID,
     time: t.Number,
     messageID: t.String,
     existingThreadDetails: createThickRawThreadInfoInputValidator,
   });
 
 export type DMLeaveThreadOperation = {
   +type: 'leave_thread',
   +editorID: string,
   +time: number,
   +messageID: string,
   +threadID: string,
 };
 export const dmLeaveThreadOperationValidator: TInterface<DMLeaveThreadOperation> =
   tShape<DMLeaveThreadOperation>({
     type: tString(dmOperationTypes.LEAVE_THREAD),
     editorID: tUserID,
     time: t.Number,
     messageID: t.String,
     threadID: t.String,
   });
 
 export type DMRemoveMembersOperation = {
   +type: 'remove_members',
   +editorID: string,
   +time: number,
   +messageID: string,
   +threadID: string,
   +removedUserIDs: $ReadOnlyArray<string>,
 };
 export const dmRemoveMembersOperationValidator: TInterface<DMRemoveMembersOperation> =
   tShape<DMRemoveMembersOperation>({
     type: tString(dmOperationTypes.REMOVE_MEMBERS),
     editorID: tUserID,
     time: t.Number,
     messageID: t.String,
     threadID: t.String,
     removedUserIDs: t.list(tUserID),
   });
 
 export type DMThreadSettingsChanges = {
   +name?: string,
   +description?: string,
   +color?: string,
-  +avatar?: ClientAvatar,
+  +avatar?: ClientAvatar | null,
 };
 
 export type DMChangeThreadSettingsOperation = $ReadOnly<{
   +type: 'change_thread_settings',
   +threadID: string,
   +editorID: string,
   +time: number,
   +changes: DMThreadSettingsChanges,
   +messageIDsPrefix: string,
 }>;
 export const dmChangeThreadSettingsOperationValidator: TInterface<DMChangeThreadSettingsOperation> =
   tShape<DMChangeThreadSettingsOperation>({
     type: tString(dmOperationTypes.CHANGE_THREAD_SETTINGS),
     threadID: t.String,
     editorID: tUserID,
     time: t.Number,
     changes: tShape({
       name: t.maybe(t.String),
       description: t.maybe(t.String),
       color: t.maybe(tColor),
       avatar: t.maybe(clientAvatarValidator),
     }),
     messageIDsPrefix: t.String,
   });
 
 export type DMChangeThreadSubscriptionOperation = {
   +type: 'change_thread_subscription',
   +time: number,
   +threadID: string,
   +creatorID: string,
   +subscription: ThreadSubscription,
 };
 export const dmChangeThreadSubscriptionOperationValidator: TInterface<DMChangeThreadSubscriptionOperation> =
   tShape<DMChangeThreadSubscriptionOperation>({
     type: tString(dmOperationTypes.CHANGE_THREAD_SUBSCRIPTION),
     time: t.Number,
     threadID: t.String,
     creatorID: tUserID,
     subscription: threadSubscriptionValidator,
   });
 
 export type DMChangeThreadReadStatusOperation = {
   +type: 'change_thread_read_status',
   +time: number,
   +threadID: string,
   +creatorID: string,
   +unread: boolean,
 };
 export const dmChangeThreadReadStatusOperationValidator: TInterface<DMChangeThreadReadStatusOperation> =
   tShape<DMChangeThreadReadStatusOperation>({
     type: tString(dmOperationTypes.CHANGE_THREAD_READ_STATUS),
     time: t.Number,
     threadID: t.String,
     creatorID: tUserID,
     unread: t.Boolean,
   });
 
 export type DMOperation =
   | DMCreateThreadOperation
   | DMCreateSidebarOperation
   | DMSendTextMessageOperation
   | DMSendReactionMessageOperation
   | DMSendEditMessageOperation
   | DMAddMembersOperation
   | DMAddViewerToThreadMembersOperation
   | DMJoinThreadOperation
   | DMLeaveThreadOperation
   | DMRemoveMembersOperation
   | DMChangeThreadSettingsOperation
   | DMChangeThreadSubscriptionOperation
   | DMChangeThreadReadStatusOperation;
 export const dmOperationValidator: TUnion<DMOperation> = t.union([
   dmCreateThreadOperationValidator,
   dmCreateSidebarOperationValidator,
   dmSendTextMessageOperationValidator,
   dmSendReactionMessageOperationValidator,
   dmSendEditMessageOperationValidator,
   dmAddMembersOperationValidator,
   dmAddViewerToThreadMembersValidator,
   dmJoinThreadOperationValidator,
   dmLeaveThreadOperationValidator,
   dmRemoveMembersOperationValidator,
   dmChangeThreadSettingsOperationValidator,
   dmChangeThreadSubscriptionOperationValidator,
   dmChangeThreadReadStatusOperationValidator,
 ]);
 
 export type DMOperationResult = {
   rawMessageInfos: Array<RawMessageInfo>,
   updateInfos: Array<ClientUpdateInfo>,
 };
 
 export const processDMOpsActionType = 'PROCESS_DM_OPS';
 
 export type ProcessDMOpsPayload = {
   +rawMessageInfos: $ReadOnlyArray<RawMessageInfo>,
   +updateInfos: $ReadOnlyArray<ClientUpdateInfo>,
   +outboundP2PMessages: ?$ReadOnlyArray<OutboundP2PMessage>,
   // For messages that could be retried from UI, we need to bind DM `messageID`
   // with `outboundP2PMessages` to keep track of whether all P2P messages
   // were queued on Tunnelbroker.
   +messageIDWithoutAutoRetry: ?string,
   +notificationsCreationData: ?NotificationsCreationData,
 };
 
 export const queueDMOpsActionType = 'QUEUE_DM_OPS';
 export type QueueDMOpsPayload = {
   +operation: DMOperation,
   +threadID: string,
   +timestamp: number,
 };
 
 export const pruneDMOpsQueueActionType = 'PRUNE_DM_OPS_QUEUE';
 export type PruneDMOpsQueuePayload = {
   +pruneMaxTimestamp: number,
 };
 
 export const clearQueuedThreadDMOpsActionType = 'CLEAR_QUEUED_THREAD_DM_OPS';
 export type ClearQueuedThreadDMOpsPayload = {
   +threadID: string,
 };
 
 export type QueuedDMOperations = {
   +operations: {
     +[threadID: string]: $ReadOnlyArray<{
       +operation: DMOperation,
       +timestamp: number,
     }>,
   },
 };
 
 export type SendDMStartedPayload = {
   +messageID: string,
 };
 
 export type SendDMOpsSuccessPayload = {
   +messageID: string,
   +outboundP2PMessageIDs: $ReadOnlyArray<string>,
 };
 
 export const sendDMActionTypes = Object.freeze({
   started: 'SEND_DM_STARTED',
   success: 'SEND_DM_SUCCESS',
   failed: 'SEND_DM_FAILED',
 });