Slack Threads Keep Showing Unread? Where the Badge Comes From
When Slack keeps showing unread messages but there are none, the badge usually comes from Threads, another workspace, the Activity or To-dos tabs, or a stale cache. Press Shift+Esc to mark everything read, open Threads, and clear the cache if the badge stays.
When Slack keeps showing unread messages but you cannot find any, the badge is coming from a place you are not looking. The usual sources are the Threads view (new replies in threads you follow), another workspace, the Activity tab (mentions), the To-dos tab (due reminders; called Later until October 2026), or a stale local cache on the desktop app. On desktop, press Shift+Esc to mark every message as read, open Threads and scroll through each thread with a new reply, then check Activity and To-dos. If a badge still shows with nothing behind it, use Help, Troubleshooting, Clear Cache and Restart.
What we saw when a thread reply arrived
We made a thread go unread on purpose on 2 October 2026, in a test workspace. We started a thread in a new channel, and a Slackbot automated reply answered inside it, so the reply came from someone else. Then we read Slack's client.counts method, which returns the numbers behind the badges, after each step. To keep one thread on screen while you read elsewhere, open it in split view, which we tested in the browser.
| Step | Threads unread (client.counts) | What the sidebar showed |
|---|---|---|
| Slackbot replied in our thread | yes, 1 for the channel | Threads in bold, the channel not bold |
| We opened the channel and saw the thread summary ("2 replies") | still yes, 1 | Threads still bold |
| We opened Threads in the sidebar | no, within 5 seconds | Threads back to normal |
So a thread reply never makes its channel bold, and reading the channel does not clear it. The Threads view does, and it marks the new reply with a New line: To see only the bold channels in the sidebar, use the Unreads filter from our test of every sidebar sort.
We also checked why unfollowed threads come back. The thread parent carries a subscribed flag. It read true, then false after we unfollowed, then true again the moment we posted a reply ourselves. Replying in a thread follows it again, so unfollow after your last reply, not before. Unfollowing is also the closest thing to closing a thread for yourself, because Slack has no Resolve button for threads and only Enterprise admins can turn replies off. If you would rather remove a thread, how to delete a thread in Slack shows why deleting the parent is not enough.
Where the unread badge comes from
| Where you see the badge | What it counts | How to clear it |
|---|---|---|
| Threads in the sidebar | New replies in threads you follow | Open Threads and read each one |
| Workspace switcher icon | Unreads in another workspace | Switch to it and read them |
| Activity tab | Mentions and reactions | Open Activity and filter to unread |
| To-dos tab | Reminders that are due | Complete or reschedule them |
| Dock or taskbar only | Stale local cache | Clear Cache and Restart |
| Phone app icon only | Push badge not yet synced | Open the app and refresh |
Muted channels do not count as unread, but a mention inside a muted channel still does. That mention also shows in the Activity tab, next to reactions, thread replies and reminders; Slack Activity tab shows its filters.
Slack threads keep showing unread
A thread counts as unread when someone replies in a thread you follow. You follow a thread when you start it, reply in it, are mentioned in it, or choose to follow it. The replies do not show in the channel, only in Threads and inside the thread itself, so people look for them in the wrong place. The exception is a reply sent with Also send to channel, which shows in both places; what Also send to channel does covers it.
To clear them:
- Click Threads at the top of your sidebar.
- Scroll through each thread with new replies until you reach the bottom.
- For threads you no longer care about, open the message menu and choose Turn off notifications for replies (unfollow). They stop coming back until you reply in them again, which follows the thread once more. Missing thread notifications have their own guide: Slack thread notifications not working.
- • Everything at once: press Shift+Esc.
- • One conversation: open it and press Esc.
- • From Unreads: press Cmd+Shift+A (Mac) or Ctrl+Shift+A (Windows), scroll to the bottom, and click Mark All Messages Read. Our test of this view, Esc and Shift+Esc is on Slack all unreads.
- • On mobile: open Catch up from Home, and press and hold Mark as Read to mark all messages read.
If a thread keeps showing as unread after you read it, reload the app with Ctrl+R or Cmd+R; the read marker may not have synced.
How to mark all Slack messages as read
To mark a message unread again on purpose, hold Option (Mac) or Alt (Windows) and click it. Every other shortcut is in our Slack keyboard shortcuts cheat sheet.
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Slack showing unread messages but there are none
When every view is empty and the badge stays:
If the badge is on your phone only, open Slack and let it sync. The icon badge comes from push notifications and updates when the app refreshes.
Why is my Slack activity notification not going away?
The Activity tab keeps its own unread state for mentions, reactions and thread replies. Open it and clear the unread items, or filter it to unread only to find the one left. If reaction lines are what fill it, Slack reaction notifications shows how to filter them out. If you get alerts for everything, adjust what counts under Preferences, Notifications; our guide to Slack notifications not working walks through each setting.
Related fixes
FAQ
Do replies from Slackbot or apps make a thread unread?
Yes. In our test the only new reply came from a Slackbot automated message, and it was enough to put Threads in bold and add 1 to the thread count.
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