diff --git a/web/chat/chat-input-bar.react.js b/web/chat/chat-input-bar.react.js
index 034a0d895..860710624 100644
--- a/web/chat/chat-input-bar.react.js
+++ b/web/chat/chat-input-bar.react.js
@@ -1,462 +1,469 @@
 // @flow
 
 import { faFileImage } from '@fortawesome/free-regular-svg-icons';
 import { faChevronRight } from '@fortawesome/free-solid-svg-icons';
 import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
 import invariant from 'invariant';
 import _difference from 'lodash/fp/difference';
 import * as React from 'react';
 
 import { joinThreadActionTypes, joinThread } from 'lib/actions/thread-actions';
 import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors';
 import { trimMessage } from 'lib/shared/message-utils';
 import {
   threadHasPermission,
   viewerIsMember,
   threadFrozenDueToViewerBlock,
   threadActualMembers,
   useRealThreadCreator,
+  threadIsPending,
 } from 'lib/shared/thread-utils';
 import type { CalendarQuery } from 'lib/types/entry-types';
 import type { LoadingStatus } from 'lib/types/loading-types';
 import { messageTypes } from 'lib/types/message-types';
 import {
   type ThreadInfo,
   threadPermissions,
   type ClientThreadJoinRequest,
   type ThreadJoinPayload,
 } from 'lib/types/thread-types';
 import { type UserInfos } from 'lib/types/user-types';
 import {
   type DispatchActionPromise,
   useServerCall,
   useDispatchActionPromise,
 } from 'lib/utils/action-utils';
 
 import {
   type InputState,
   type PendingMultimediaUpload,
 } from '../input/input-state';
 import LoadingIndicator from '../loading-indicator.react';
 import { allowedMimeTypeString } from '../media/file-utils';
 import Multimedia from '../media/multimedia.react';
 import FailedSendModal from '../modals/chat/failed-send.react';
 import { useSelector } from '../redux/redux-utils';
 import { nonThreadCalendarQuery } from '../selectors/nav-selectors';
 import css from './chat-message-list.css';
 
 type BaseProps = {|
   +threadInfo: ThreadInfo,
   +inputState: InputState,
   +setModal: (modal: ?React.Node) => void,
 |};
 type Props = {|
   ...BaseProps,
   // Redux state
   +viewerID: ?string,
   +joinThreadLoadingStatus: LoadingStatus,
   +calendarQuery: () => CalendarQuery,
   +nextLocalID: number,
   +isThreadActive: boolean,
   +userInfos: UserInfos,
   // Redux dispatch functions
   +dispatchActionPromise: DispatchActionPromise,
   // async functions that hit server APIs
   +joinThread: (request: ClientThreadJoinRequest) => Promise<ThreadJoinPayload>,
   +getServerThreadID: () => Promise<?string>,
 |};
 class ChatInputBar extends React.PureComponent<Props> {
   textarea: ?HTMLTextAreaElement;
   multimediaInput: ?HTMLInputElement;
 
   componentDidMount() {
     this.updateHeight();
     if (this.props.isThreadActive) {
       this.addReplyListener();
     }
   }
 
   componentWillUnmount() {
     if (this.props.isThreadActive) {
       this.removeReplyListener();
     }
   }
 
   componentDidUpdate(prevProps: Props) {
     if (this.props.isThreadActive && !prevProps.isThreadActive) {
       this.addReplyListener();
     } else if (!this.props.isThreadActive && prevProps.isThreadActive) {
       this.removeReplyListener();
     }
 
     const { inputState } = this.props;
     const prevInputState = prevProps.inputState;
     if (inputState.draft !== prevInputState.draft) {
       this.updateHeight();
     }
     const curUploadIDs = ChatInputBar.unassignedUploadIDs(
       inputState.pendingUploads,
     );
     const prevUploadIDs = ChatInputBar.unassignedUploadIDs(
       prevInputState.pendingUploads,
     );
     if (
       this.multimediaInput &&
       _difference(prevUploadIDs)(curUploadIDs).length > 0
     ) {
       // Whenever a pending upload is removed, we reset the file
       // HTMLInputElement's value field, so that if the same upload occurs again
       // the onChange call doesn't get filtered
       this.multimediaInput.value = '';
     } else if (
       this.textarea &&
       _difference(curUploadIDs)(prevUploadIDs).length > 0
     ) {
       // Whenever a pending upload is added, we focus the textarea
       this.textarea.focus();
       return;
     }
 
     if (this.props.threadInfo.id !== prevProps.threadInfo.id && this.textarea) {
       this.textarea.focus();
     }
   }
 
   static unassignedUploadIDs(
     pendingUploads: $ReadOnlyArray<PendingMultimediaUpload>,
   ) {
     return pendingUploads
       .filter(
         (pendingUpload: PendingMultimediaUpload) => !pendingUpload.messageID,
       )
       .map((pendingUpload: PendingMultimediaUpload) => pendingUpload.localID);
   }
 
   updateHeight() {
     const textarea = this.textarea;
     if (textarea) {
       textarea.style.height = 'auto';
       const newHeight = Math.min(textarea.scrollHeight, 150);
       textarea.style.height = `${newHeight}px`;
     }
   }
 
   addReplyListener() {
     invariant(
       this.props.inputState,
       'inputState should be set in addReplyListener',
     );
     this.props.inputState.addReplyListener(this.focusAndUpdateText);
   }
 
   removeReplyListener() {
     invariant(
       this.props.inputState,
       'inputState should be set in removeReplyListener',
     );
     this.props.inputState.removeReplyListener(this.focusAndUpdateText);
   }
 
   render() {
     const isMember = viewerIsMember(this.props.threadInfo);
     const canJoin = threadHasPermission(
       this.props.threadInfo,
       threadPermissions.JOIN_THREAD,
     );
     let joinButton = null;
     if (!isMember && canJoin) {
       let buttonContent;
       if (this.props.joinThreadLoadingStatus === 'loading') {
         buttonContent = (
           <LoadingIndicator
             status={this.props.joinThreadLoadingStatus}
             size="medium"
             color="white"
           />
         );
       } else {
         buttonContent = <span className={css.joinButtonText}>Join Thread</span>;
       }
       joinButton = (
         <div className={css.joinButtonContainer}>
           <a onClick={this.onClickJoin}>{buttonContent}</a>
         </div>
       );
     }
 
     const { pendingUploads, cancelPendingUpload } = this.props.inputState;
     const multimediaPreviews = pendingUploads.map((pendingUpload) => (
       <Multimedia
         uri={pendingUpload.uri}
         pendingUpload={pendingUpload}
         remove={cancelPendingUpload}
         multimediaCSSClass={css.multimedia}
         multimediaImageCSSClass={css.multimediaImage}
         key={pendingUpload.localID}
       />
     ));
     const previews =
       multimediaPreviews.length > 0 ? (
         <div className={css.previews}>{multimediaPreviews}</div>
       ) : null;
 
     let content;
     if (threadHasPermission(this.props.threadInfo, threadPermissions.VOICED)) {
       const sendIconStyle = { color: `#${this.props.threadInfo.color}` };
+      let multimediaInput = null;
+      if (!threadIsPending(this.props.threadInfo.id)) {
+        multimediaInput = (
+          <a className={css.multimediaUpload} onClick={this.onMultimediaClick}>
+            <input
+              type="file"
+              onChange={this.onMultimediaFileChange}
+              ref={this.multimediaInputRef}
+              accept={allowedMimeTypeString}
+              multiple
+            />
+            <FontAwesomeIcon icon={faFileImage} />
+          </a>
+        );
+      }
       content = (
         <div className={css.inputBarTextInput}>
           <textarea
             rows="1"
             placeholder="Send a message..."
             value={this.props.inputState.draft}
             onChange={this.onChangeMessageText}
             onKeyDown={this.onKeyDown}
             ref={this.textareaRef}
             autoFocus
           />
-          <a className={css.multimediaUpload} onClick={this.onMultimediaClick}>
-            <input
-              type="file"
-              onChange={this.onMultimediaFileChange}
-              ref={this.multimediaInputRef}
-              accept={allowedMimeTypeString}
-              multiple
-            />
-            <FontAwesomeIcon icon={faFileImage} />
-          </a>
+          {multimediaInput}
           <a className={css.send} onClick={this.onSend}>
             <FontAwesomeIcon
               icon={faChevronRight}
               className={css.sendButton}
               style={sendIconStyle}
             />
             Send
           </a>
         </div>
       );
     } else if (
       threadFrozenDueToViewerBlock(
         this.props.threadInfo,
         this.props.viewerID,
         this.props.userInfos,
       ) &&
       threadActualMembers(this.props.threadInfo.members).length === 2
     ) {
       content = (
         <span className={css.explanation}>
           You can&apos;t send messages to a user that you&apos;ve blocked.
         </span>
       );
     } else if (isMember) {
       content = (
         <span className={css.explanation}>
           You don&apos;t have permission to send messages.
         </span>
       );
     } else {
       const defaultRoleID = Object.keys(this.props.threadInfo.roles).find(
         (roleID) => this.props.threadInfo.roles[roleID].isDefault,
       );
       invariant(
         defaultRoleID !== undefined,
         'all threads should have a default role',
       );
       const defaultRole = this.props.threadInfo.roles[defaultRoleID];
       const membersAreVoiced = !!defaultRole.permissions[
         threadPermissions.VOICED
       ];
       if (membersAreVoiced && canJoin) {
         content = (
           <span className={css.explanation}>
             Join this thread to send messages.
           </span>
         );
       } else {
         content = (
           <span className={css.explanation}>
             You don&apos;t have permission to send messages.
           </span>
         );
       }
     }
 
     return (
       <div className={css.inputBar}>
         {joinButton}
         {previews}
         {content}
       </div>
     );
   }
 
   textareaRef = (textarea: ?HTMLTextAreaElement) => {
     this.textarea = textarea;
     if (textarea) {
       textarea.focus();
     }
   };
 
   onChangeMessageText = (event: SyntheticEvent<HTMLTextAreaElement>) => {
     this.props.inputState.setDraft(event.currentTarget.value);
   };
 
   focusAndUpdateText = (text: string) => {
     // We need to call focus() first on Safari, otherwise the cursor
     // ends up at the start instead of the end for some reason
     const { textarea } = this;
     invariant(textarea, 'textarea should be set');
     textarea.focus();
 
     // We reset the textarea to an empty string at the start so that the cursor
     // always ends up at the end, even if the text doesn't actually change
     textarea.value = '';
     const currentText = this.props.inputState.draft;
     if (!currentText.startsWith(text)) {
       const prependedText = text.concat(currentText);
       this.props.inputState.setDraft(prependedText);
       textarea.value = prependedText;
     } else {
       textarea.value = currentText;
     }
 
     // The above strategies make sure the cursor is at the end,
     // but we also need to make sure that we're scrolled to the bottom
     textarea.scrollTop = textarea.scrollHeight;
   };
 
   onKeyDown = (event: SyntheticKeyboardEvent<HTMLTextAreaElement>) => {
     if (event.keyCode === 13 && !event.shiftKey) {
       event.preventDefault();
       this.send();
     }
   };
 
   onSend = async (event: SyntheticEvent<HTMLAnchorElement>) => {
     event.preventDefault();
     await this.send();
   };
 
   async send() {
     let { nextLocalID } = this.props;
 
     const text = trimMessage(this.props.inputState.draft);
     if (text) {
       // TODO we should make the send button appear dynamically
       // iff trimmed text is nonempty, just like native
       await this.dispatchTextMessageAction(text, nextLocalID);
       nextLocalID++;
     }
 
     this.props.inputState.createMultimediaMessage(nextLocalID);
   }
 
   async dispatchTextMessageAction(text: string, nextLocalID: number) {
     this.props.inputState.setDraft('');
 
     const localID = `local${nextLocalID}`;
     const creatorID = this.props.viewerID;
     invariant(creatorID, 'should have viewer ID in order to send a message');
 
     const threadID = await this.props.getServerThreadID();
     if (!threadID) {
       return;
     }
 
     this.props.inputState.sendTextMessage({
       type: messageTypes.TEXT,
       localID,
       threadID,
       text,
       creatorID,
       time: Date.now(),
     });
   }
 
   multimediaInputRef = (multimediaInput: ?HTMLInputElement) => {
     this.multimediaInput = multimediaInput;
   };
 
   onMultimediaClick = () => {
     if (this.multimediaInput) {
       this.multimediaInput.click();
     }
   };
 
   onMultimediaFileChange = async (
     event: SyntheticInputEvent<HTMLInputElement>,
   ) => {
     const result = await this.props.inputState.appendFiles([
       ...event.target.files,
     ]);
     if (!result && this.multimediaInput) {
       this.multimediaInput.value = '';
     }
   };
 
   onClickJoin = (event: SyntheticEvent<HTMLAnchorElement>) => {
     event.preventDefault();
     this.props.dispatchActionPromise(joinThreadActionTypes, this.joinAction());
   };
 
   async joinAction() {
     const query = this.props.calendarQuery();
     return await this.props.joinThread({
       threadID: this.props.threadInfo.id,
       calendarQuery: {
         startDate: query.startDate,
         endDate: query.endDate,
         filters: [
           ...query.filters,
           { type: 'threads', threadIDs: [this.props.threadInfo.id] },
         ],
       },
     });
   }
 }
 
 const joinThreadLoadingStatusSelector = createLoadingStatusSelector(
   joinThreadActionTypes,
 );
 
 export default React.memo<BaseProps>(function ConnectedChatInputBar(
   props: BaseProps,
 ) {
   const viewerID = useSelector(
     (state) => state.currentUserInfo && state.currentUserInfo.id,
   );
   const nextLocalID = useSelector((state) => state.nextLocalID);
   const isThreadActive = useSelector(
     (state) => props.threadInfo.id === state.navInfo.activeChatThreadID,
   );
   const userInfos = useSelector((state) => state.userStore.userInfos);
   const joinThreadLoadingStatus = useSelector(joinThreadLoadingStatusSelector);
   const calendarQuery = useSelector(nonThreadCalendarQuery);
   const dispatchActionPromise = useDispatchActionPromise();
   const callJoinThread = useServerCall(joinThread);
 
   const { setModal } = props;
   const showErrorModal = React.useCallback(
     () => setModal(<FailedSendModal setModal={setModal} />),
     [setModal],
   );
   const sourceMessageID = useSelector((state) => state.navInfo.sourceMessageID);
   const getServerThreadID = useRealThreadCreator(
     { threadInfo: props.threadInfo, sourceMessageID },
     showErrorModal,
   );
 
   return (
     <ChatInputBar
       {...props}
       viewerID={viewerID}
       joinThreadLoadingStatus={joinThreadLoadingStatus}
       calendarQuery={calendarQuery}
       nextLocalID={nextLocalID}
       isThreadActive={isThreadActive}
       userInfos={userInfos}
       dispatchActionPromise={dispatchActionPromise}
       joinThread={callJoinThread}
       getServerThreadID={getServerThreadID}
     />
   );
 });
diff --git a/web/chat/chat-message-list.react.js b/web/chat/chat-message-list.react.js
index 798274d56..b07b5ea3e 100644
--- a/web/chat/chat-message-list.react.js
+++ b/web/chat/chat-message-list.react.js
@@ -1,481 +1,486 @@
 // @flow
 
 import classNames from 'classnames';
 import { detect as detectBrowser } from 'detect-browser';
 import invariant from 'invariant';
 import * as React from 'react';
 import { useDrop } from 'react-dnd';
 import { NativeTypes } from 'react-dnd-html5-backend';
 
 import {
   fetchMessagesBeforeCursorActionTypes,
   fetchMessagesBeforeCursor,
   fetchMostRecentMessagesActionTypes,
 } from 'lib/actions/message-actions';
 import { registerFetchKey } from 'lib/reducers/loading-reducer';
 import {
   type ChatMessageItem,
   useMessageListData,
 } from 'lib/selectors/chat-selectors';
 import { threadInfoSelector } from 'lib/selectors/thread-selectors';
 import { messageKey } from 'lib/shared/message-utils';
-import { useWatchThread, useCurrentThreadInfo } from 'lib/shared/thread-utils';
+import {
+  useWatchThread,
+  useCurrentThreadInfo,
+  threadIsPending,
+} from 'lib/shared/thread-utils';
 import type { FetchMessageInfosPayload } from 'lib/types/message-types';
 import { type ThreadInfo } from 'lib/types/thread-types';
 import {
   type DispatchActionPromise,
   useServerCall,
   useDispatchActionPromise,
 } from 'lib/utils/action-utils';
 
 import { type InputState, InputStateContext } from '../input/input-state';
 import LoadingIndicator from '../loading-indicator.react';
 import { useTextMessageRulesFunc } from '../markdown/rules.react';
 import { useSelector } from '../redux/redux-utils';
 import ChatInputBar from './chat-input-bar.react';
 import css from './chat-message-list.css';
 import { MessageListContext } from './message-list-types';
 import MessageTimestampTooltip from './message-timestamp-tooltip.react';
 import Message from './message.react';
 import type {
   OnMessagePositionWithContainerInfo,
   MessagePositionInfo,
 } from './position-types';
 
 type BaseProps = {|
   +setModal: (modal: ?React.Node) => void,
 |};
 type PassedProps = {|
   ...BaseProps,
   // Redux state
   +activeChatThreadID: ?string,
   +threadInfo: ?ThreadInfo,
   +messageListData: ?$ReadOnlyArray<ChatMessageItem>,
   +startReached: boolean,
   +timeZone: ?string,
   +supportsReverseFlex: boolean,
   // Redux dispatch functions
   +dispatchActionPromise: DispatchActionPromise,
   // async functions that hit server APIs
   +fetchMessagesBeforeCursor: (
     threadID: string,
     beforeMessageID: string,
   ) => Promise<FetchMessageInfosPayload>,
   // withInputState
   +inputState: ?InputState,
 |};
 type ReactDnDProps = {|
   isActive: boolean,
   connectDropTarget: (node: React.Node) => React.Node,
 |};
 type Props = {|
   ...PassedProps,
   ...ReactDnDProps,
 |};
 type State = {|
   +mouseOverMessagePosition: ?OnMessagePositionWithContainerInfo,
 |};
 type Snapshot = {|
   +scrollTop: number,
   +scrollHeight: number,
 |};
 class ChatMessageList extends React.PureComponent<Props, State> {
   state: State = {
     mouseOverMessagePosition: null,
   };
   container: ?HTMLDivElement;
   messageContainer: ?HTMLDivElement;
   loadingFromScroll = false;
 
   componentDidMount() {
     this.scrollToBottom();
   }
 
   getSnapshotBeforeUpdate(prevProps: Props) {
     if (
       ChatMessageList.hasNewMessage(this.props, prevProps) &&
       this.messageContainer
     ) {
       const { scrollTop, scrollHeight } = this.messageContainer;
       return { scrollTop, scrollHeight };
     }
     return null;
   }
 
   static hasNewMessage(props: Props, prevProps: Props) {
     const { messageListData } = props;
     if (!messageListData || messageListData.length === 0) {
       return false;
     }
     const prevMessageListData = prevProps.messageListData;
     if (!prevMessageListData || prevMessageListData.length === 0) {
       return true;
     }
     return (
       ChatMessageList.keyExtractor(prevMessageListData[0]) !==
       ChatMessageList.keyExtractor(messageListData[0])
     );
   }
 
   componentDidUpdate(prevProps: Props, prevState: State, snapshot: ?Snapshot) {
     const { messageListData } = this.props;
     const prevMessageListData = prevProps.messageListData;
 
     if (
       this.loadingFromScroll &&
       messageListData &&
       (!prevMessageListData ||
         messageListData.length > prevMessageListData.length ||
         this.props.startReached)
     ) {
       this.loadingFromScroll = false;
     }
 
     const { messageContainer } = this;
     if (messageContainer && prevMessageListData !== messageListData) {
       this.onScroll();
     }
 
     // We'll scroll to the bottom if the user was already scrolled to the bottom
     // before the new message, or if the new message was composed locally
     const hasNewMessage = ChatMessageList.hasNewMessage(this.props, prevProps);
     if (
       this.props.activeChatThreadID !== prevProps.activeChatThreadID ||
       (hasNewMessage &&
         messageListData &&
         messageListData[0].itemType === 'message' &&
         messageListData[0].messageInfo.localID) ||
       (hasNewMessage && snapshot && Math.abs(snapshot.scrollTop) <= 1)
     ) {
       this.scrollToBottom();
     } else if (hasNewMessage && messageContainer && snapshot) {
       const { scrollTop, scrollHeight } = messageContainer;
       if (
         scrollHeight > snapshot.scrollHeight &&
         scrollTop === snapshot.scrollTop
       ) {
         const newHeight = scrollHeight - snapshot.scrollHeight;
         const newScrollTop = Math.abs(scrollTop) + newHeight;
         if (this.props.supportsReverseFlex) {
           messageContainer.scrollTop = -1 * newScrollTop;
         } else {
           messageContainer.scrollTop = newScrollTop;
         }
       }
     }
   }
 
   scrollToBottom() {
     if (this.messageContainer) {
       this.messageContainer.scrollTop = 0;
     }
   }
 
   static keyExtractor(item: ChatMessageItem) {
     if (item.itemType === 'loader') {
       return 'loader';
     }
     return messageKey(item.messageInfo);
   }
 
   renderItem = (item) => {
     if (item.itemType === 'loader') {
       return (
         <div key="loader" className={css.loading}>
           <LoadingIndicator status="loading" size="large" color="black" />
         </div>
       );
     }
     const { threadInfo, setModal } = this.props;
     invariant(threadInfo, 'ThreadInfo should be set if messageListData is');
     return (
       <Message
         item={item}
         threadInfo={threadInfo}
         setMouseOverMessagePosition={this.setMouseOverMessagePosition}
         mouseOverMessagePosition={this.state.mouseOverMessagePosition}
         setModal={setModal}
         timeZone={this.props.timeZone}
         key={ChatMessageList.keyExtractor(item)}
       />
     );
   };
 
   setMouseOverMessagePosition = (messagePositionInfo: MessagePositionInfo) => {
     if (!this.messageContainer) {
       return;
     }
     if (messagePositionInfo.type === 'off') {
       this.setState({ mouseOverMessagePosition: null });
       return;
     }
     const {
       top: containerTop,
       bottom: containerBottom,
       left: containerLeft,
       right: containerRight,
       height: containerHeight,
       width: containerWidth,
     } = this.messageContainer.getBoundingClientRect();
     const mouseOverMessagePosition = {
       ...messagePositionInfo,
       messagePosition: {
         ...messagePositionInfo.messagePosition,
         top: messagePositionInfo.messagePosition.top - containerTop,
         bottom: messagePositionInfo.messagePosition.bottom - containerTop,
         left: messagePositionInfo.messagePosition.left - containerLeft,
         right: messagePositionInfo.messagePosition.right - containerLeft,
       },
       containerPosition: {
         top: containerTop,
         bottom: containerBottom,
         left: containerLeft,
         right: containerRight,
         height: containerHeight,
         width: containerWidth,
       },
     };
     this.setState({ mouseOverMessagePosition });
   };
 
   render() {
     const {
       messageListData,
       threadInfo,
       inputState,
       connectDropTarget,
       isActive,
       setModal,
     } = this.props;
     if (!messageListData) {
       return <div className={css.container} />;
     }
     invariant(threadInfo, 'ThreadInfo should be set if messageListData is');
     invariant(inputState, 'InputState should be set');
     const messages = messageListData.map(this.renderItem);
     const containerStyle = classNames({
       [css.container]: true,
       [css.activeContainer]: isActive,
     });
 
     let tooltip;
     if (this.state.mouseOverMessagePosition) {
       const messagePositionInfo = this.state.mouseOverMessagePosition;
       tooltip = (
         <MessageTimestampTooltip
           messagePositionInfo={messagePositionInfo}
           timeZone={this.props.timeZone}
         />
       );
     }
 
     const messageContainerStyle = classNames({
       [css.messageContainer]: true,
       [css.mirroredMessageContainer]: !this.props.supportsReverseFlex,
     });
     return connectDropTarget(
       <div className={containerStyle} ref={this.containerRef}>
         <div className={css.outerMessageContainer}>
           <div className={messageContainerStyle} ref={this.messageContainerRef}>
             {messages}
           </div>
           {tooltip}
         </div>
         <ChatInputBar
           threadInfo={threadInfo}
           inputState={inputState}
           setModal={setModal}
         />
       </div>,
     );
   }
 
   containerRef = (container: ?HTMLDivElement) => {
     if (container) {
       container.addEventListener('paste', this.onPaste);
     }
     this.container = container;
   };
 
   onPaste = (e: ClipboardEvent) => {
     const { inputState } = this.props;
     if (!inputState) {
       return;
     }
     const { clipboardData } = e;
     if (!clipboardData) {
       return;
     }
     const { files } = clipboardData;
     if (files.length === 0) {
       return;
     }
     e.preventDefault();
     inputState.appendFiles([...files]);
   };
 
   messageContainerRef = (messageContainer: ?HTMLDivElement) => {
     this.messageContainer = messageContainer;
     // In case we already have all the most recent messages,
     // but they're not enough
     this.possiblyLoadMoreMessages();
     if (messageContainer) {
       messageContainer.addEventListener('scroll', this.onScroll);
     }
   };
 
   onScroll = () => {
     if (!this.messageContainer) {
       return;
     }
     if (this.state.mouseOverMessagePosition) {
       this.setState({ mouseOverMessagePosition: null });
     }
     this.possiblyLoadMoreMessages();
   };
 
   possiblyLoadMoreMessages() {
     if (!this.messageContainer) {
       return;
     }
     const { scrollTop, scrollHeight, clientHeight } = this.messageContainer;
     if (
       this.props.startReached ||
       Math.abs(scrollTop) + clientHeight + 55 < scrollHeight
     ) {
       return;
     }
     const oldestMessageServerID = this.oldestMessageServerID();
     if (!oldestMessageServerID) {
       return;
     }
     if (this.loadingFromScroll) {
       return;
     }
     this.loadingFromScroll = true;
     const threadID = this.props.activeChatThreadID;
     invariant(threadID, 'should be set');
     this.props.dispatchActionPromise(
       fetchMessagesBeforeCursorActionTypes,
       this.props.fetchMessagesBeforeCursor(threadID, oldestMessageServerID),
     );
   }
 
   oldestMessageServerID(): ?string {
     const data = this.props.messageListData;
     invariant(data, 'should be set');
     for (let i = data.length - 1; i >= 0; i--) {
       if (data[i].itemType === 'message' && data[i].messageInfo.id) {
         return data[i].messageInfo.id;
       }
     }
     return null;
   }
 }
 
 registerFetchKey(fetchMessagesBeforeCursorActionTypes);
 registerFetchKey(fetchMostRecentMessagesActionTypes);
 
 export default React.memo<BaseProps>(function ConnectedChatMessageList(
   props: BaseProps,
 ) {
   const userAgent = useSelector((state) => state.userAgent);
   const supportsReverseFlex = React.useMemo(() => {
     const browser = detectBrowser(userAgent);
     return (
       !browser || browser.name !== 'firefox' || parseInt(browser.version) >= 81
     );
   }, [userAgent]);
 
   const timeZone = useSelector((state) => state.timeZone);
 
   const activeChatThreadID = useSelector(
     (state) => state.navInfo.activeChatThreadID,
   );
   const baseThreadInfo = useSelector((state) => {
     const activeID = state.navInfo.activeChatThreadID;
     if (!activeID) {
       return null;
     }
     return threadInfoSelector(state)[activeID] ?? state.navInfo.pendingThread;
   });
   const sourceMessageID = useSelector((state) => state.navInfo.sourceMessageID);
   const threadInfo = useCurrentThreadInfo({
     baseThreadInfo,
     searching: false,
     userInfoInputArray: [],
     sourceMessageID,
   });
 
   const messageListData = useMessageListData({
     sourceMessageID,
     searching: false,
     userInfoInputArray: [],
     threadInfo,
   });
 
   const startReached = useSelector((state) => {
     const activeID = state.navInfo.activeChatThreadID;
     if (!activeID) {
       return null;
     }
 
     if (state.navInfo.pendingThread) {
       return true;
     }
 
     const threadMessageInfo = state.messageStore.threads[activeID];
     if (!threadMessageInfo) {
       return null;
     }
     return threadMessageInfo.startReached;
   });
 
   const dispatchActionPromise = useDispatchActionPromise();
   const callFetchMessagesBeforeCursor = useServerCall(
     fetchMessagesBeforeCursor,
   );
 
   const inputState = React.useContext(InputStateContext);
   const [dndProps, connectDropTarget] = useDrop({
     accept: NativeTypes.FILE,
     drop: (item) => {
       const { files } = item;
       if (inputState && files.length > 0) {
         inputState.appendFiles(files);
       }
     },
     collect: (monitor) => ({
       isActive: monitor.isOver() && monitor.canDrop(),
     }),
+    canDrop: () => !threadIsPending(activeChatThreadID),
   });
 
   const getTextMessageMarkdownRules = useTextMessageRulesFunc(threadInfo?.id);
   const messageListContext = React.useMemo(() => {
     if (!getTextMessageMarkdownRules) {
       return undefined;
     }
     return { getTextMessageMarkdownRules };
   }, [getTextMessageMarkdownRules]);
 
   useWatchThread(threadInfo);
 
   return (
     <MessageListContext.Provider value={messageListContext}>
       <ChatMessageList
         {...props}
         activeChatThreadID={activeChatThreadID}
         threadInfo={threadInfo}
         messageListData={messageListData}
         startReached={startReached}
         timeZone={timeZone}
         supportsReverseFlex={supportsReverseFlex}
         inputState={inputState}
         dispatchActionPromise={dispatchActionPromise}
         fetchMessagesBeforeCursor={callFetchMessagesBeforeCursor}
         {...dndProps}
         connectDropTarget={connectDropTarget}
       />
     </MessageListContext.Provider>
   );
 });