Slack Images Not Showing? 5 Causes We Reproduced

When images in Slack show up as a file name with a small arrow instead of a picture, a display setting or a collapse is hiding them. The image is still there. Click the arrow next to the file name to open one image. To fix all of them, open Preferences, Messages & media, and tick Show images and files uploaded to Slack. On 10 October 2026 we reproduced five causes in a Slack test channel on the web app and the Free plan.

Cause 1: an image setting is off

Slack has four switches under Preferences, Messages & media, Inline media & links:

The change applied to our open Slack tab at once, with no reload. These are your own preferences, so a coworker who sees the images has different settings, not a different message.

Cause 2: someone ran /collapse

Typing /collapse in a channel hides every uploaded file in it for you. Slack answered with "I've collapsed all files in this channel for you." In our test, link previews stayed open after /collapse; only uploaded files closed. Type /expand to open them again, and Slack answers "I've expanded all files in this channel for you."

Cause 3: one file was collapsed by its arrow

The small arrow next to a file name is labelled "Toggle attachment". One click hides that one image. We clicked it, reloaded the page, and the image stayed hidden, so the choice is saved. Click the arrow again to bring the image back.

Cause 4: the link has no preview

We posted the same kind of link to two image hosts. A PNG on our own storage got an image preview whether we sent it from the message box or the API. A thumbnail URL on upload.wikimedia.org stayed a plain blue link both times we posted it. So a missing preview can come from the site behind the link. Uploading the image to Slack avoids that. To remove previews on purpose, see how to turn off link previews in Slack.

Cause 5: an app's upload never finished

Many "images not appearing in Slack post" threads come from bots and integrations. Our test app uploaded two images with files.getUploadURLExternal, then called files.completeUploadExternal for a channel the bot had not joined. Slack answered:

{'ok': False, 'error': 'not_in_channel'}

Nothing appeared in the channel. The upload step had returned HTTP 200, so the integration looked fine unless it checked the second response. The same two files posted fine when we sent them from an account that was in the channel, so add the app to the channel before it uploads. Large files have their own rules, see Slack file size limit, and Slack's previews are smaller than the originals, see does Slack compress images.

Questions

Why do images show for my coworker but not for me?

The image settings and /collapse are per person. Check your own Messages & media settings and run /expand in the channel.

Does /collapse hide images for everyone?

No. Slack's reply to /collapse was marked "Only visible to you", and it said it collapsed the files "for you". Other people in the channel still see the images.

Is the image deleted when it does not show?

No. In every case above, the file was still in the message, and one click or one setting brought it back.