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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 Later tabs, or a stale cache. Press Shift+Esc to mark everything read, open Threads, and clear the cache if the badge stays.

Slack Green Team
September 23, 2026
October 3, 2026
4 min read
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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 Later tab (due reminders), 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 Later. 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.

StepThreads unread (client.counts)What the sidebar showed
Slackbot replied in our threadyes, 1 for the channelThreads in bold, the channel not bold
We opened the channel and saw the thread summary ("2 replies")still yes, 1Threads still bold
We opened Threads in the sidebarno, within 5 secondsThreads back to normal
Slack sidebar after a reply in a followed thread: Threads in bold while the channel the thread lives in, sg1002-threads, is not bold; rows in between removed

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:

Slack Threads view with the thread parent, our reply and the Slackbot reply below a red New line

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.

Where the unread badge comes from

Where you see the badgeWhat it countsHow to clear it
Threads in the sidebarNew replies in threads you followOpen Threads and read each one
Workspace switcher iconUnreads in another workspaceSwitch to it and read them
Activity tabMentions and reactionsOpen Activity and filter to unread
Later tabReminders that are dueComplete or reschedule them
Dock or taskbar onlyStale local cacheClear Cache and Restart
Phone app icon onlyPush badge not yet syncedOpen the app and refresh

Muted channels do not count as unread, but a mention inside a muted channel still does.

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.

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.
  • 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

  • • 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.
  • 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:

  • Check the other workspaces. A dot on another workspace icon adds to the app badge.
  • Check Later. Due reminders put a badge on Later and Activity.
  • Reload. Press Ctrl+R or Cmd+R.
  • Clear the cache. On the desktop app, open the Help menu, then Troubleshooting, then Clear Cache and Restart. Your messages and settings stay on Slack's servers; only local files reset. The same step helps when Slack is slow or uses too much memory; see why Slack uses so much memory. If the app icon still shows a red dot after all four, the stale badge belongs to your operating system; resetting it on Mac, Windows and phones is in Slack red dot won't go away.
  • Update Slack. Old versions keep stale badges more often.
  • Sign out and back in if nothing else works.
  • 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 you get alerts for everything, adjust what counts under Preferences, Notifications; our guide to Slack notifications not working walks through each setting.

  • • Channels missing rather than stuck: Slack channels disappeared from the sidebar.
  • • Due reminders you forgot: Slack /remind command examples covers listing and deleting them.
  • • Notifications paused with a z on your name: Slack Do Not Disturb.
  • 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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