Microsoft Teams Is Damaged and Can’t Be Opened — Here’s How to Fix It

You open your laptop, click on Microsoft Teams, and instead of seeing your chats, you get hit with this message:

“Microsoft Teams is damaged and can’t be opened. You should move it to the Trash.”

Or maybe Teams just refuses to launch on Windows — no error message, no loading screen, just nothing.

Either way, it’s frustrating, especially when you have a meeting in 10 minutes.

I’ve been through this myself, and the good news is — it’s almost always fixable without calling IT. In this tutorial, I’ll walk you through every reliable fix I know, starting with the simplest ones. Try them in order and you’ll likely be back in Teams within a few minutes.

Why Does This Happen?

Before jumping into fixes, it helps to understand what’s actually going wrong. There are a few common culprits:

• macOS Gatekeeper — Your Mac quarantines apps it doesn’t fully trust, especially after an update. Teams gets flagged as “damaged” even though it’s perfectly fine.
• A bad auto-update — Microsoft’s auto-updater sometimes pushes a broken build. This is more common than you’d think.
• Corrupted cache files — Teams stores a lot of temporary data locally. When those files get corrupted, Teams can refuse to open.
• Incomplete installation — If Teams was interrupted during install or update, leftover broken files stick around and cause issues.
• Windows app data conflicts — On Windows, leftover registry entries or app packages from older installs can block Teams from launching.

Now let’s fix it. If Teams opens fine but then won’t load chats or connect, that’s a different problem, and this guide on why Microsoft Teams is not working is the better place to start.

Fix 1: Restart Teams Completely (Windows & Mac)

This sounds too simple, but Teams sometimes gets stuck in a background process. It looks closed but it’s actually still running — and that prevents it from opening fresh.

On Windows:

• Press Ctrl + Shift + Esc to open Task Manager
• Look for any process named Microsoft Teams (new Teams runs as ms-teams.exe on the Details tab)
• Right-click it and select End Task
• Now try opening Teams again

On Mac:

• Click the Apple menu → Force Quit
• Select Microsoft Teams and click Force Quit
• Reopen Teams from Applications

If Teams still won’t open, move to the next fix. (Several stuck Teams processes can also eat RAM; here’s why Microsoft Teams is using a lot of memory.)

Fix 2: Remove the Quarantine Attribute on Mac (The #1 Mac Fix)

If you’re on a Mac and seeing the “Microsoft Teams is damaged and can’t be opened” message, there’s a very good chance this is a macOS Gatekeeper issue, not an actual Teams problem. macOS tags downloaded apps with a quarantine attribute. Sometimes it incorrectly flags Teams — especially after an auto-update — and refuses to let it open.

The fix? Tell your Mac to drop the quarantine flag.

Here’s how:

1. Open Finder → Applications → Utilities → Terminal
2. Type or paste this command exactly:

xattr -d com.apple.quarantine /Applications/Microsoft\ Teams.app

3. Press Enter
4. Try opening Teams again

That’s it. In most cases, this single command fixes the “damaged” error immediately.

If Terminal says the file doesn’t exist, the app has a slightly different name on your Mac. Type xattr -d com.apple.quarantine (with the trailing space), drag the Teams app from Applications into the Terminal window to fill in the exact path, and press Return.

One word of caution. Apple says a “damaged” alert means macOS detected that the app was modified or corrupted. Only remove the flag from a copy of Teams you downloaded from Microsoft yourself. If you aren’t sure where your copy came from, skip to Fix 7 and reinstall it fresh.

What does this command do? The xattr command manages extended file attributes on macOS. The flag com.apple.quarantine is what macOS adds to downloaded files to flag them for Gatekeeper inspection. Removing it tells macOS: “I trust this app, let it run.”

If you get a message saying “No such xattr: com.apple.quarantine,” it means the attribute wasn’t set in the first place. In that case, skip to the next fix.

Fix 3: Right-Click to Open (Quick Gatekeeper Bypass on Mac)

If you’d rather not use Terminal, there’s a simpler workaround that bypasses Gatekeeper for a single launch:

1. Open Finder → Applications
2. Find Microsoft Teams
3. Right-click (or Control-click) on it
4. Select Open from the menu
5. A warning dialog will appear — click Open again

This tells macOS you’re intentionally choosing to open this app. After doing this once, macOS usually remembers your choice and Teams opens normally going forward.

On macOS Sequoia and later, Control-click > Open no longer gets you past the warning. Apple’s current way is the Open Anyway button in System Settings > Privacy & Security, which I cover in Fix 5.

Fix 4: Clear the Teams Cache (Windows & Mac)

Corrupted cache files are one of the most common reasons Teams won’t open — on both Windows and Mac. Clearing the cache forces Teams to rebuild those files fresh on the next launch. Don’t worry, it doesn’t delete your messages or contacts. That data lives in the cloud.

On Windows:

1. Make sure Teams is fully closed (right-click the Teams icon in the taskbar and select Quit, or use Task Manager)
2. Press Windows + R to open the Run dialog
3. Type %userprofile%\appdata\local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams and press Enter (that’s the new Teams folder; old classic Teams used %appdata%\Microsoft\Teams)
4. Select everything inside that folder (Ctrl + A)
5. Delete it all (the files and folders inside, not the MSTeams folder itself)
6. Restart Teams

On Mac:

1. Quit Teams completely
2. Open Finder and click Go in the menu bar
3. Hold the Option (⌥) key — this reveals the hidden Library folder
4. Click Library
5. Go to Group Containers and delete the UBF8T346G9.com.microsoft.teams folder
6. Go back to Library → Containers and delete the com.microsoft.teams2 folder too
7. Reopen Teams

Prefer Terminal? Microsoft gives these two commands for new Teams on a Mac (quit Teams first):

rm -rf ~/Library/Group\ Containers/UBF8T346G9.com.microsoft.teams
rm -rf ~/Library/Containers/com.microsoft.teams2

After clearing the cache, Teams may take a little longer to load the first time — that’s normal. It’s just rebuilding. For every step with screenshots, follow this guide to clear Microsoft Teams cache.

Fix 5: Check Privacy & Security Settings on Mac

Sometimes macOS blocks Teams outright and shows a notice in System Settings. You might have missed it.

1. Open System Settings (or System Preferences on older macOS)
2. Go to Privacy & Security
3. Scroll down to the Security section
4. Look for a message saying Microsoft Teams was blocked to protect your Mac
5. Click Open Anyway

macOS shows the warning one more time; select Open to confirm. If you see that prompt, clicking it is all you need to do. Teams should open normally after that. If there’s no Open Anyway button, macOS isn’t blocking Teams there, so move on to the cache and reinstall fixes.

Fix 6: Delete Registry Entries on Windows

If Teams won’t open on Windows even after clearing the cache, there may be leftover registry keys causing the conflict. This happens when a previous installation didn’t clean up after itself properly. These keys belong to the old classic Teams, so this fix only helps on PCs that once had classic Teams installed.

⚠️ Before editing the registry, always back it up. Go to File → Export in Registry Editor to save a copy.

Here’s what to do:

1. Press Windows + R, type regedit, and press Enter
2. Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Office\Teams
3. If this folder exists, right-click it and select Delete
4. Also check: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Teams
5. Delete it if present
6. Close Registry Editor and restart your PC
7. Try opening Teams again

This clears any corrupted or outdated Teams configuration that Windows was holding onto.

Fix 7: Fully Uninstall and Reinstall Teams

If nothing above has worked, it’s time for a clean reinstall. The key here is making sure you remove all traces of Teams before reinstalling — otherwise the broken files just come right back.

On Windows:

1. Go to Settings → Apps → Installed Apps
2. Search for Microsoft Teams and uninstall it
3. Also uninstall Teams Machine-Wide Installer if you see it
4. Delete these folders manually:
   • %LocalAppData%\Packages\MSTeams_8wekyb3d8bbwe
   • %ProgramData%\Microsoft\Teams
   • %AppData%\Microsoft\Teams
5. Restart your PC
6. Download the latest Teams from Microsoft’s official page at microsoft.com/microsoft-teams/download-app
7. Install and sign in

On Mac:

1. Quit Teams
2. Open Finder → Applications and drag Microsoft Teams to the Trash
3. Open Finder, press Command + Shift + G, and go to ~/Library/Containers/
4. Delete the com.microsoft.teams2 folder
5. Also go to ~/Library/Group Containers/ and delete UBF8T346G9.com.microsoft.teams
6. Empty the Trash
7. Download a fresh copy of Teams from the official Microsoft download page (the Mac version is a .pkg installer that works on both Intel and Apple silicon Macs)
8. Install and reopen

Pro tip: On a work Mac or PC that your company manages, Teams may be installed through Self Service or Company Portal. Reinstall it from there, or ask IT, so you get the version your organization supports.

Fix 8: Make Sure Your macOS Version Is Still Supported

This is a lesser-known cause. Microsoft supports the Teams desktop app only on the three most recent versions of macOS. When a new macOS version comes out, the oldest one drops off the list, and a fresh Teams build may refuse to open on it.

1. Click the Apple menu → About This Mac and note your macOS version
2. Open System Settings → General → Software Update and install any available macOS update

3. Restart your Mac
4. Try opening Teams again

If your Mac is too old for a supported macOS version, use Teams on the web at teams.microsoft.com in Safari, Chrome, or Edge. It doesn’t need an install, so the “damaged” error can’t happen there.

Fix 9: Repair or Reset Teams on Windows

New Teams is a packaged Windows app, so Windows can repair or reset it for you without a full reinstall.

1. Open Settings → Apps → Installed apps and search for Microsoft Teams
2. Select More options (…) next to it → Advanced options
3. Under Reset, select Repair first and try Teams again
4. If it still won’t open, select Reset (this deletes the app’s local data, including your personal settings) and restart Teams

If Teams still won’t open on a work device after that, talk to your IT admin, since a device policy may be blocking it. If it opens but then shows a warning icon, see what the Microsoft Teams red triangle exclamation mark means.

Quick Reference: Which Fix for Which Situation?

Situation	Best Fix to Try First
Mac shows “damaged and can’t be opened”	Fix 2 (xattr Terminal command)
Teams silently won’t open on Mac	Fix 4 (clear cache) or Fix 8 (check macOS version)
Teams not opening on Windows	Fix 4 (clear cache)
Tried reinstalling but issue keeps returning	Fix 6 (registry cleanup) + Fix 7 (clean reinstall)
Auto-update broke Teams	Fix 7 (clean reinstall with fresh download)
Teams still won’t start on Windows	Fix 9 (Repair, then Reset)
Work/managed device	Self Service or Company Portal reinstall, then your IT admin

One More Thing Before You Go

If Teams keeps breaking after an auto-update on Mac, don’t turn updates off. On a Mac, Teams is updated through Microsoft AutoUpdate, and Microsoft expects you to stay on a current version (Teams starts warning you once your version is one to three months old). Instead, open Microsoft AutoUpdate (you can find it via Spotlight) and select Check for Updates. A fixed build usually follows a bad one quickly.

Also, keep an eye on the Microsoft Teams Community Hub and Microsoft Q&A pages. When a broken build goes out, the community usually reports it within hours. You’ll know quickly whether the issue is on your end or Microsoft’s.

Frequently Asked Questions

Once Teams opens again, these guides help you keep it running smoothly:

• Blocked by a device policy instead? Fix your organization has disabled this device.
• Don’t want Teams launching at every login? Here’s how to stop Microsoft Teams from opening on startup.
• Camera dark after the reinstall? Try these fixes for the camera not working in Microsoft Teams.
• Want to set the app up again quickly? Walk through the Microsoft Teams settings that matter most.