Microsoft 365, Teams, or Outlook Not Working? Fix the Most Common Errors

Microsoft apps go down, freeze, or throw error codes at the worst times. Before you call IT, here are the five most common reasons Microsoft 365, Teams, and Outlook stop working — ranked from most frequent to least — with a direct fix for each.

Reason #5: Microsoft Service Outage

Before touching any settings, check whether the problem is on Microsoft's end.

• Go to status.microsoft365.com — active incidents are listed in real time.
• Check @MSFT365Status on Twitter/X for live updates.
• Search "Microsoft Teams down" or "Outlook down" on Downdetector.

If there's an active incident: nothing to fix on your side. Microsoft typically resolves service incidents within 1–4 hours. If no outage is listed, continue to Reason #4.

Reason #4: Outdated App Version

Microsoft pushes security patches and bug fixes through app updates — running an old version causes sign-in failures, missing features, and sync errors that look like connectivity problems.

Update Microsoft 365 (Desktop):

1. Open any Office app (Word, Excel, Outlook).
2. Go to File → Account → Update Options → Update Now.
3. Restart all Office apps after updating.

Update Teams:

1. Click the three-dot menu (…) next to your profile picture in Teams.
2. Select Check for updates.
3. Teams will update in the background — restart the app after it completes.

Update on Mobile:

Go to the App Store (iPhone) or Google Play (Android), search for Microsoft Teams or Outlook, and tap Update if available.

Reason #3: Corrupted Outlook Profile or Teams Cache

Both Outlook and Teams store local caches that can become corrupted after an unexpected shutdown, a failed update, or a disk error. A corrupted cache causes slow loading, missing emails, and login loops.

Clear Teams Cache (Windows):

1. Fully quit Teams (right-click the taskbar icon → Quit).
2. Press Windows + R, type %appdata%\Microsoft\Teams, press Enter.
3. Delete the contents of these folders: Cache, blob_storage, databases, GPUCache, IndexedDB, Local Storage, tmp.
4. Reopen Teams — it will rebuild the cache on first load (takes 1–2 minutes).

Repair Outlook Profile:

1. Close Outlook.
2. Open Control Panel → Mail → Show Profiles → select your profile → Properties → Email Accounts.
3. Select your account and click Repair.
4. Follow the prompts and reopen Outlook.

Reason #2: Sign-In / Authentication Token Expired

Microsoft 365 uses OAuth tokens that expire. When they do, apps silently fail to connect — you may see a yellow bar in Outlook saying "Disconnected" or a Teams error saying "We couldn't sign you in."

Fix for Outlook:

1. Look for a yellow "Disconnected" or "Need Password" bar at the bottom of Outlook.
2. Click it and re-enter your Microsoft account password.
3. If the bar doesn't appear: go to File → Office Account → Sign Out, then Sign In again.

Fix for Teams:

1. Click your profile picture → Sign Out.
2. Close Teams completely.
3. Reopen and sign in with your Microsoft 365 account.

Fix for Web Apps (Office.com):

1. Go to office.com and click Sign Out.
2. Clear browser cookies for microsoft.com: Chrome → Settings → Privacy → Cookies → See all cookies → search "microsoft" → Delete all.
3. Sign back in.

Reason #1: License or Subscription Issue

This is the most common cause of Microsoft 365 stopping without warning. A lapsed subscription, a failed payment, or an admin removing your license causes apps to enter "read-only" mode or show "Your account doesn't allow editing on a Mac/PC."

Check Your Subscription Status:

1. Go to account.microsoft.com/services and sign in.
2. Check whether your Microsoft 365 subscription shows as Active or Expired.
3. If expired: click Renew and update your payment method.

If You're on a Work or School Account:

Your IT admin controls your license. Check with them if your subscription shows as active but apps still don't work — an admin may have reassigned or removed your license without notification.

Fix "Unlicensed Product" Error:

1. Open any Office app → File → Account.
2. If it shows "Unlicensed Product" or "Product Deactivated": click Sign In and use the email address that holds the active Microsoft 365 subscription.
3. If you have multiple Microsoft accounts, make sure you're signed in with the one that has the active license — not a personal account.

Bonus: Microsoft 365 on Mac — Common Extra Issues

• Keychain access denied: Mac may block Office from accessing saved credentials. Go to Keychain Access → search "Microsoft" → delete all Microsoft entries → reopen Office and sign in fresh.
• Teams camera/mic not working on Mac: Go to System Settings → Privacy & Security → Camera/Microphone and confirm Microsoft Teams has permission.
• Outlook not syncing on Mac: Go to Tools → Accounts → select account → Advanced → Folders → Reset to force a full re-sync.

Bottom Line

The majority of Microsoft 365, Teams, and Outlook failures come down to four things: a service outage (check first), an expired auth token (sign out and back in), a corrupted cache (clear it), or a lapsed license (check account.microsoft.com). Start with the service status check — it saves you time if the issue is on Microsoft's end — then work through the authentication and cache fixes, which together resolve most user-side problems in under five minutes.

Getting a specific error code? Drop it in the comments and we'll look it up.