Slack Not Working? Fix Every Common Slack Problem in 2026

Disclosure: TechSifted is an independent review and troubleshooting site. We're not affiliated with Slack or Salesforce.

Slack failing during a work day is legitimately disruptive. Messages you sent might not have arrived. Notifications you needed to see haven't appeared. A call that was supposed to work just... didn't.

Most of these problems have quick fixes. Let's work through them.

Start Here: Check Slack's Status

Before spending time on local troubleshooting, check status.slack.com.

Slack has occasional service incidents that affect specific features or specific regions. If there's an active incident and it matches your problem, you'll know immediately that waiting is the right answer. They usually resolve within a few hours and post updates on the status page.

All green on the status page? Then your problem is local — keep reading.

Fix: Messages Not Sending

The first symptom of Slack trouble is usually that the spinner on a message just... keeps spinning. Or you see a red error indicator on a sent message.

Step 1: Check your connection. Open a browser tab and try loading a website. If the internet is down, that's your problem. On mobile, check if you're on Wi-Fi or a weak cellular signal.

Step 2: Look for the offline indicator. In the Slack desktop app, if you're offline, you'll see a small lightning bolt or network icon in the toolbar indicating you're disconnected. Click it — Slack will attempt to reconnect.

Step 3: Force close and reopen. Sometimes Slack's connection to its servers silently breaks — the app appears connected but messages aren't transmitting. Fully close the app (Cmd+Q on Mac, not just closing the window) and reopen it.

Step 4: Check workspace status. If messages are sending in one workspace but not another, the issue may be specific to that workspace. Try sending a message in a different workspace or DM.

Step 5: Try the web version. Open slack.com in a browser. If the web version works but the desktop app doesn't, the issue is with your local Slack installation — reinstall.

Fix: Notifications Not Showing

Slack notifications failing is the most common complaint I hear, and it almost always comes from one of these three places. Check all three.

Layer 1: OS-level notifications

On iPhone/iPad: Settings > Notifications > Slack

• Make sure "Allow Notifications" is toggled on
• Check that "Alerts" and/or "Lock Screen" is enabled
• Check that Slack's notification style isn't set to None

On Android: Settings > Apps > Slack > Notifications

• Enable notifications
• Make sure a notification channel isn't blocked

On Mac: System Settings > Notifications > Slack

• Allow notifications must be on
• Sound, badges, or banners must be enabled for the notification to appear

On Windows: Settings > System > Notifications > Slack

• Notifications must be on

Layer 2: Focus/Do Not Disturb modes

iPhones in Focus mode or Do Not Disturb will block Slack notifications even if the above settings are correct. Check your Focus settings (Control Center, or Settings > Focus). You can add Slack as an allowed app if you want Slack to break through Focus mode.

Mac's Do Not Disturb and Focus modes work the same way.

Layer 3: Slack's own notification settings

Inside Slack, go to Preferences > Notifications. This controls which types of messages notify you.

Common misconfiguration: "Mobile push notifications" set to "Nothing" instead of "Direct messages, mentions & keywords" or "All new messages." If this is set to Nothing, you won't get any phone notifications regardless of OS settings.

Also check whether your workspace has scheduled quiet hours configured. Some workspace admins set quiet hours that suppress notifications outside work hours.

Also: Are you active on too many devices?
Slack has a "delivery setting" that controls when mobile notifications fire — by default, Slack only sends mobile notifications when you haven't been active on desktop for a few minutes. If you're on your laptop, mobile notifications won't fire. This is intentional behavior, not a bug.

Fix: Slack Calls Not Working

Slack Calls (both the built-in Slack Huddles and Slack's call feature) can fail for a few reasons.

Microphone/camera permissions: First time on a new device or after an app reinstall, Slack needs permission to use your microphone and camera. On Mac: System Settings > Privacy & Security > Microphone (and Camera) — Slack must be checked. On Windows: Settings > Privacy > Microphone — toggle must be on.

Huddles audio problems: If you can join a Huddle but no one can hear you (or you can't hear them):

• Check the audio device setting in Slack — click the audio gear in the Huddle interface and select the correct microphone/speakers
• Make sure no other app (Teams, Zoom, Google Meet) is exclusively using your microphone
• Restart the Huddle — close it and rejoin

Calls not connecting: Slack calls require specific network ports. Corporate firewalls sometimes block these. If calls fail only on your work network but work on home or cellular, talk to your IT department about Slack call connectivity.

Video not showing in Slack calls: Check that the camera isn't physically covered (laptop cameras with privacy shutters), that camera permissions are granted to Slack, and that another app isn't exclusively using the camera.

Fix: Desktop App Crashing

Slack desktop app crashes are usually one of three things: a memory issue, a corrupted cache, or a corrupted installation.

Clear the Slack cache:

• Mac: Quit Slack. Open Finder, press Cmd+Shift+G, paste ~/Library/Application Support/Slack/Cache. Delete all contents of this folder. Restart Slack.
• Windows: Quit Slack. Open File Explorer, navigate to %AppData%\Slack\Cache. Delete all contents. Restart Slack.
• Linux: rm -rf ~/.config/Slack/Cache

Cache issues cause crashes, weird visual glitches, and sluggish performance. Clear it regularly if you're having issues.

Update Slack: Outdated versions have bugs that newer versions fix. Go to Help > Check for Updates (Mac) or the equivalent on Windows.

Clean reinstall if cache clearing doesn't help:

• Uninstall Slack via your Applications folder (Mac) or Settings > Apps (Windows)
• On Mac, also delete ~/Library/Application Support/Slack and ~/Library/Caches/com.tinyspeck.slackmacgap
• Restart your computer
• Download and reinstall from slack.com/downloads

Fix: File Uploads Failing

Files refusing to upload is straightforward to diagnose.

Check file size: Slack's upload limits are 1GB per file for paid plans and 1MB for free workspaces. Most failures come from trying to upload large videos or high-resolution images. Compress the file or use a file sharing service (Google Drive, Dropbox) and paste a link instead.

Check connection stability: Large uploads require a stable connection throughout the upload process. If you're on a spotty Wi-Fi signal, switch to ethernet or wait for a better signal.

Check storage quota: Free Slack workspaces have a limited file storage quota. If the workspace is full, uploads fail. A workspace admin can delete old files or upgrade the plan.

Try a different file format: Occasionally specific file types trigger upload failures. If a HEIC photo won't upload, convert it to JPEG first.

Fix: Channels Not Loading

If specific channels in Slack show blank or keep loading but never display messages:

Reload the channel: Click away to another channel, then click back. Or press Ctrl+Shift+R (Cmd+Shift+R on Mac) to force reload Slack.

Check message history: Very old channels with extremely long message histories sometimes load slowly. Give it a few minutes.

Check permissions: If a channel is showing "Loading..." indefinitely, there may be a workspace permission issue — you may have had access removed. Check with a workspace admin.

Try the web version: If a channel loads in the browser (slack.com) but not in the desktop app, the issue is desktop app-specific — reinstall.

Quick Reference

Problem	First fix
Messages not sending	Check connection, force close/reopen
Notifications missing	Check OS permissions > Slack preferences
Calls not connecting	Check mic permissions, try cellular network
App crashing	Clear cache, then update
Files won't upload	Check file size, check connection
Channels not loading	Reload, check with workspace admin

For more on comparing Slack with Microsoft Teams for your team, see our Slack vs. Microsoft Teams 2026 comparison.

When to Contact Slack Support

Contact support at slack.com/help if:

• Messages are missing from channels (possible data issue)
• Billing or workspace administration problems
• Enterprise Grid connectivity issues
• Single Sign-On failures
• The above troubleshooting hasn't resolved the issue

Paid workspace admins get priority support. Free workspace users get community support via the Slack Help Center.