Single video attachments not visible when image previews are collapsed (v11.10.0)

Adit Yadav

Updated August 18, 2026 07:02

Problem

On Mattermost v11.10.0, a post containing a single video attachment is hidden for any user whose image previews are set to collapsed. The message text still appears, but the video is not shown and there is no control to expand it, so the attachment appears not to exist.

This affects the display only. The video file is uploaded and stored on the server as normal, and is not altered or removed.

Symptoms

A post known to have a video attached shows only the message text, with an empty gap or nothing where the attachment should appear.
There is no thumbnail and no expand control, so the video cannot be opened, played, or downloaded from the post.
Other users can see the video on the same post. Whether it appears depends on each viewer's own display setting.
Affected users have Settings > Display > Default Appearance of Image Previews set to Collapsed, or have run /collapse.
Single images, and posts with two or more attachments, are not affected. Only single videos disappear.
The issue does not occur in the mobile app.

Cause

In v11.10.0, the expand control for a single video attachment is not displayed when image previews are collapsed. With both the video and its expand control hidden, nothing remains visible on the post.

This was introduced in v11.10.0 and does not affect v11.9 or earlier releases.

Solution

Set image previews to expanded to restore the affected videos immediately. A permanent fix is planned for an upcoming v11.10 patch release.

Restore the hidden videos

Each affected user should run the following command in any channel:

/expand

The hidden videos appear again immediately. The same change can be made through Settings > Display > Default Appearance of Image Previews by selecting Expanded.

This setting applies per user and takes effect straight away. No server restart, administrator action, or re-uploading of videos is required.

Permanent fix

A fix has been completed and is planned for an upcoming v11.10 patch release, which restores the expand control for collapsed single videos. Once it is applied, the collapsed preview setting can be used again as normal.

Servers still running v11.10.0 can use the workaround above in the meantime. Earlier releases are not affected.

Verify

Set image previews back to Collapsed, then open a post with a single video attachment. A collapsed header showing 1 item should be visible, and selecting it should expand and play the video.

Important: No video files are lost or damaged. Attachments remain intact on the server and reappear as soon as the display setting is changed or the fix is applied. Deleting and re-uploading a video will not help while previews remain collapsed.

Additional Resources

For more information, see:

Manage your display options — Mattermost documentation
Mattermost server releases — Mattermost documentation