diff --git a/app/javascript/mastodon/features/compose/components/upload_progress.tsx b/app/javascript/mastodon/features/compose/components/upload_progress.tsx
index 35af03306f..be15917784 100644
--- a/app/javascript/mastodon/features/compose/components/upload_progress.tsx
+++ b/app/javascript/mastodon/features/compose/components/upload_progress.tsx
@@ -9,48 +9,39 @@ import { reduceMotion } from 'mastodon/initial_state';
 interface UploadProgressProps {
   active: boolean;
   progress: number;
-  isProcessing: boolean;
+  isProcessing?: boolean;
 }
 
 export const UploadProgress: React.FC<UploadProgressProps> = ({
   active,
   progress,
-  isProcessing,
+  isProcessing = false,
 }) => {
   const styles = useSpring({
     from: { width: '0%' },
     to: { width: `${progress}%` },
-    reset: true,
-    immediate: reduceMotion,
+    immediate: reduceMotion || !active, // If this is not active, update the UI immediately.
   });
   if (!active) {
     return null;
   }
 
-  let message;
-
-  if (isProcessing) {
-    message = (
-      <FormattedMessage
-        id='upload_progress.processing'
-        defaultMessage='Processing…'
-      />
-    );
-  } else {
-    message = (
-      <FormattedMessage
-        id='upload_progress.label'
-        defaultMessage='Uploading…'
-      />
-    );
-  }
-
   return (
     <div className='upload-progress'>
       <Icon id='upload' icon={UploadFileIcon} />
 
       <div className='upload-progress__message'>
-        {message}
+        {isProcessing ? (
+          <FormattedMessage
+            id='upload_progress.processing'
+            defaultMessage='Processing…'
+          />
+        ) : (
+          <FormattedMessage
+            id='upload_progress.label'
+            defaultMessage='Uploading…'
+          />
+        )}
 
         <div className='upload-progress__backdrop'>
           <animated.div className='upload-progress__tracker' style={styles} />
diff --git a/app/javascript/mastodon/reducers/compose.js b/app/javascript/mastodon/reducers/compose.js
index d16c8a0d2e..73468c04fe 100644
--- a/app/javascript/mastodon/reducers/compose.js
+++ b/app/javascript/mastodon/reducers/compose.js
@@ -113,6 +113,7 @@ function clearAll(state) {
     map.set('sensitive', state.get('default_sensitive'));
     map.set('language', state.get('default_language'));
     map.update('media_attachments', list => list.clear());
+    map.set('progress', 0);
     map.set('poll', null);
     map.set('idempotencyKey', uuid());
   });
@@ -128,6 +129,7 @@ function appendMedia(state, media, file) {
     map.update('media_attachments', list => list.push(media.set('unattached', true)));
     map.set('is_uploading', false);
     map.set('is_processing', false);
+    map.set('progress', 0);
     map.set('resetFileKey', Math.floor((Math.random() * 0x10000)));
     map.set('idempotencyKey', uuid());
     map.update('pending_media_attachments', n => n - 1);
@@ -296,6 +298,8 @@ const updatePoll = (state, index, value, maxOptions) => state.updateIn(['poll',
   return tmp;
 });
 
+const calculateProgress = (loaded, total) => Math.min(Math.round((loaded / total) * 100), 100);
+
 /** @type {import('@reduxjs/toolkit').Reducer<typeof initialState>} */
 export const composeReducer = (state = initialState, action) => {
   if (changeUploadCompose.fulfilled.match(action)) {
@@ -402,15 +406,19 @@ export const composeReducer = (state = initialState, action) => {
   case COMPOSE_UPLOAD_SUCCESS:
     return appendMedia(state, fromJS(action.media), action.file);
   case COMPOSE_UPLOAD_FAIL:
-    return state.set('is_uploading', false).set('is_processing', false).update('pending_media_attachments', n => n - 1);
+    return state
+      .set('is_uploading', false)
+      .set('is_processing', false)
+      .set('progress', 0)
+      .update('pending_media_attachments', n => n - 1);
   case COMPOSE_UPLOAD_UNDO:
     return removeMedia(state, action.media_id);
   case COMPOSE_UPLOAD_PROGRESS:
-    return state.set('progress', Math.round((action.loaded / action.total) * 100));
+    return state.set('progress', calculateProgress(action.loaded, action.total));
   case THUMBNAIL_UPLOAD_REQUEST:
     return state.set('isUploadingThumbnail', true);
   case THUMBNAIL_UPLOAD_PROGRESS:
-    return state.set('thumbnailProgress', Math.round((action.loaded / action.total) * 100));
+    return state.set('thumbnailProgress', calculateProgress(action.loaded, action.total));
   case THUMBNAIL_UPLOAD_FAIL:
     return state.set('isUploadingThumbnail', false);
   case THUMBNAIL_UPLOAD_SUCCESS: