FIX: Slack couldn’t upload your file

Aleksandar Ognjanovic
by Aleksandar Ognjanovic
Troubleshooting Expert
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  • Slack is a collaboration software that allows you to communicate and share files in real-time with your team members.
  • If Slack can’t upload your files, you need to check your Internet connection and clear the application cache.
  • If you’re interested in more information about Slack and other similar tools, we suggest you check out our productivity software hub.
  • If you’re having additional problems with Slack, we suggest checking out our Slack errors hub for more in-depth guides.
slack processing uploaded file stuck

Slack checks all the boxes when it comes to team organization and collaboration. It’s one of the most popular, feature-rich applications out there.

The complete control over your workspace is guaranteed and the reliability rarely fails. However, you’ve probably run into a few rare errors which might be cumbersome.

One of those prevents users from uploading files to Slack as they’re promptly informed that Slack couldn’t upload your file. There are a few solutions for this below.

What can I do if Slack can’t upload my file?

  1. Check your internet connection
  2. Clear application cache (for desktop and UWP versions)
  3. Check Firewall
  4. Reinstall the app

1. Check your Internet connection

  1. Navigate to Slack web-based connection-testing tool.
  2. Sign in with your account.
  3. Make sure everything is up and running.

If the test tool didn’t fix your problem, move to the next solution.


2. Clear application cache

Slack client for Desktop

  1. Open Slack.
  2. Click on the hamburger menu in the top left corner and choose Help > Troubleshooting > Clear cache and Restart.slack reset cache desktop client slack can't upload files
  3. You can repeat the action and clear app‘s data as well.

Slack UWP from Microsoft Store

  1. Open Start.
  2. Right-click on the Slack app and choose More > App settings from the contextual menu.
  3. Try firstly with the Repair and, if it doesn’t work, go for the Reset option.slack reset app cache slack can't upload files

Browser cache

  1. Press Shift + Ctrl + Delete to open the Clear browsing data menu.
  2. Select All time as the time range.
  3. Focus on deleting Cookies, Cached Images and Files, and other site data.clear browser cache slack can't upload files
  4. Click on the Clear Data button.

After doing that, check if the problem with Slack and file upload is still there.


3. Check Firewall

  1. In the Windows Search bar, type Firewall, and open Allow an app through Windows Firewall.
  2. Click Change settings.
    change firewall settings slack can't upload files
  3. Allow Slack to communicate freely by checking both boxes.
  4. Confirm changes and restart your PC.
  5. Start Slack and look for changes.

4. Reinstall the app

Finally, if none of the steps proved fruitful and you’re still stuck with the Slack couldn’t upload your file error, consider reinstalling the desktop client/UWP app.

We still can’t be sure whether this helps or not, but it’s a viable step when something goes wrong with other apps. Slack isn’t an exception.


Need to uninstall Slack completely? Do that with one of these uninstaller applications!


With that said, we can conclude this article. In case you have any questions or suggestions, consider sharing them with us in the comments section below.

FAQ: Learn more about Slack

  • How does Slack store data?

Slack stores all data on its servers. This includes your messages and uploaded files.

  • Can you edit documents in Slack?

Slack has a built-in simple text editor that lets you edit documents. Just click the + icon and choose the Post option. Select the desired channel and check Let others edit this post option.

  • Can you upload videos to Slack?

Yes, you can upload video files to Slack just like any other file type as long as you have enough storage space available on Slack.

  • Does Slack have a file size limit?

File size limit when uploading files to Slack is 1GB per file.

Editor’s Note: This post was originally published in January 2019 and has been since revamped and updated in March 2020 for freshness, accuracy, and comprehensiveness.