Skip to main content
Even with a smooth Microsoft 365 setup, you may occasionally hit a snag. Activation errors, sign-in problems, app crashes, and sync failures are among the most common issues users encounter — and nearly all of them have straightforward fixes you can apply yourself in just a few minutes. This guide covers the problems reported most often, with clear, step-by-step solutions for each one so you can get back to work as quickly as possible.
The Microsoft Support and Recovery Assistant (aka.ms/SaRA) is a free tool from Microsoft that automatically diagnoses and fixes many common Office, Outlook, and Teams problems. When in doubt, run it first — it handles dozens of issues without any manual steps.
If you’re on a business plan, some issues — such as licence assignment, mailbox policies, or tenant-level settings — can only be resolved by your IT administrator. Contact your IT team if the steps below don’t resolve a business-account issue.

​
Activation & Licensing Issues

If your apps are showing a banner saying your subscription has expired or you’re in “reduced functionality” mode, follow these steps:
  1. Go to account.microsoft.com/subscriptions and sign in with the account you used to purchase Microsoft 365.
  2. Check the subscription status. If it shows Expired, click Renew or Reactivate.
  3. If the payment failed, click Update payment to add a new card or payment method. Microsoft sends several reminder emails before a subscription lapses, so also check your spam folder for any missed notices.
  4. Once payment is confirmed, open any Microsoft 365 app and go to File > Account. Click Update Licence or sign out and sign back in — the activated status should appear within a few minutes.
If you’re on a business plan and the subscription appears active in the admin portal but apps still show an expiry notice, your IT admin may need to re-assign the licence to your account.
An “Account Notice” or “Product Activation Failed” banner in Word, Excel, or another app usually means the app has lost its connection to your Microsoft account or licence. Try these steps in order:
  1. Sign out and sign back in: In the app, go to File > Account > Sign Out, then sign back in with your Microsoft 365 account. This refreshes the licence token.
  2. Check you’re signed in with the correct account: Make sure you’re using the email address associated with your paid subscription — not a personal Microsoft account if you have a work or school licence.
  3. Run the Microsoft Support and Recovery Assistant: Download from aka.ms/SaRA and select Office as the app. It will diagnose and repair activation issues automatically.
  4. Run an Office Repair: Go to Windows Settings > Apps > Installed Apps, find Microsoft 365, click the three-dot menu, and select Modify. Choose Quick Repair first; if the problem persists, choose Online Repair (requires internet access and takes longer but is more thorough).
If you’ve purchased Microsoft 365 but can’t find the download or your product key isn’t working, here’s how to get started correctly:
  1. Go to microsoft365.com/setup and sign in with the exact Microsoft account you used at the time of purchase. A common mistake is signing in with a different email address.
  2. If you bought a physical copy (boxed retail), you’ll need to enter the product key printed inside the box — do this at microsoft365.com/setup before downloading.
  3. Once signed in, you should see an Install Office or Install apps button. Click it to download the installer for your platform.
  4. If the install button is missing, check that your subscription is active at account.microsoft.com/subscriptions.
  5. On a business plan, your Microsoft 365 apps may need to be assigned to you by an admin before the install option appears — check with your IT team.

​
Sign-In Problems

Resetting your Microsoft account password is straightforward as long as you have access to a recovery method:
  1. Go to account.microsoft.com and click Sign in, then Forgot my password on the sign-in screen.
  2. Enter your email address or phone number, then complete the CAPTCHA.
  3. Choose your recovery method — Microsoft will send a verification code to your recovery email address or mobile phone number.
  4. Enter the code and create a new, strong password.
If you no longer have access to your recovery email or phone number, select I don’t have any of these and follow the account recovery form. Microsoft may ask you to verify your identity with details like previous passwords or billing information.
Microsoft temporarily locks accounts after multiple consecutive failed sign-in attempts to protect against brute-force attacks. This is a security feature, not a permanent lock:
  1. Wait 30 minutes and try signing in again with the correct password. In most cases, the lock is lifted automatically.
  2. If you’re unsure of your password, use the Forgot password reset flow at account.microsoft.com rather than attempting more guesses.
  3. If you’ve waited and still can’t sign in, use the Microsoft account recovery form to regain access through identity verification.
  4. For work or school accounts that are locked, contact your IT administrator — they can unlock the account immediately from the Microsoft 365 admin centre.
If your SMS verification code is delayed or not arriving at all, try the following:
  1. Check your phone signal — poor reception or a no-service area will prevent SMS delivery. Move to an area with better signal and request a new code.
  2. Request the code again — codes expire after a few minutes; click Resend code on the sign-in screen to get a fresh one.
  3. Check for carrier delays — occasionally mobile networks experience temporary SMS delays. Wait a couple of minutes and try again.
  4. Switch to Microsoft Authenticator — the authenticator app generates codes offline and is far more reliable than SMS. Set it up at aka.ms/mfasetup by adding it as a new security method. Once configured, you’ll no longer depend on SMS delivery.
  5. Use a backup code — if you saved backup codes when setting up MFA, use one of those to sign in and then update your MFA settings.

​
App & Performance Issues

If Word, Excel, PowerPoint, or another app crashes immediately when you open it, the most efficient first step is the Support and Recovery Assistant:
  1. Download and run the Microsoft Support and Recovery Assistant from aka.ms/SaRA. Select the affected application and follow the prompts — it will check for and repair common causes automatically.
  2. If SaRA doesn’t resolve it, try starting the app in Safe Mode to disable add-ins: hold the Ctrl key while clicking the app icon (Windows). If the app opens in Safe Mode, an add-in is causing the crash. Go to File > Options > Add-ins, set Manage to COM Add-ins, click Go, and uncheck add-ins one at a time to identify the culprit.
  3. Run an Online Repair via Windows Settings > Apps > Microsoft 365 > Modify > Online Repair.
  4. As a last resort, uninstall Microsoft 365 using the Office Uninstall Support Tool and reinstall from microsoft365.com.
Sluggish performance in Office apps is usually caused by a combination of add-ins, graphics rendering, and installation issues:
  1. Disable hardware graphics acceleration: Go to File > Options > Advanced, scroll to the Display section, and check Disable hardware graphics acceleration. Restart the app. This often resolves slowness on older graphics cards or in virtual machine environments.
  2. Disable unnecessary add-ins: Go to File > Options > Add-ins, manage COM Add-ins, and disable any third-party add-ins you don’t actively use.
  3. Reduce document complexity: Very large documents with many high-resolution images, complex formulas, or tracked changes can slow performance. Try compressing images (Picture Format > Compress Pictures) or splitting large documents.
  4. Repair the Office installation: Go to Windows Settings > Apps > Microsoft 365 > Modify and run a Quick Repair to fix corrupted files.
  5. Check available RAM: Microsoft 365 apps perform best with at least 4 GB of RAM. If your device is near its memory limit, close unused applications while working.
When OneDrive stops syncing, files you edit locally won’t be updated in the cloud (and vice versa). Work through these steps:
  1. Check the OneDrive icon in the system tray: A cloud icon with a cross or pause symbol indicates a sync problem. Click it to see the error message — OneDrive usually explains exactly what’s wrong.
  2. Check available disk space: OneDrive can’t sync if your local drive is full. Free up space and syncing will resume automatically.
  3. Check your internet connection: OneDrive requires an active internet connection to sync. If you’re on a metered connection, OneDrive may be paused to save data — click the OneDrive icon and click Resume syncing.
  4. Sign out and sign back in: Right-click the OneDrive icon > Settings > Account > Unlink this PC, then sign in again to re-establish the sync connection.
  5. Reset OneDrive: If other steps fail, reset OneDrive to its default state. Press Win + R, type %localappdata%\Microsoft\OneDrive\OneDrive.exe /reset, and press Enter. Wait for the icon to reappear (this may take a few minutes), then sign in again.
If new emails have stopped appearing in Outlook, the issue is almost always one of the following:
  1. Check the Junk Email folder: Legitimate messages sometimes get caught by spam filters. If you find expected emails in Junk, right-click and select Not junk so future messages are delivered correctly.
  2. Check Inbox rules: Go to File > Manage Rules & Alerts and look for any rules that might be moving, deleting, or redirecting incoming mail. Disable or delete any rules you didn’t intentionally create — hackers who gain account access sometimes add forwarding rules.
  3. Check your mailbox storage quota: If your mailbox is full, new emails will be rejected. In Outlook, go to File > Info to see your mailbox size. Delete old emails or empty the Deleted Items folder to free up space. Business users can ask their admin to increase their quota.
  4. Check your email filtering and connection status: In Outlook, look at the status bar at the bottom — it should say Connected to Microsoft Exchange or All folders are up to date. If it shows Disconnected or Working Offline, click Send/Receive > Work Offline to toggle back to online mode.
  5. Run the SaRA tool for Outlook: aka.ms/SaRA has a dedicated Outlook diagnostic that checks mail flow, profile settings, and connectivity automatically.

​
Teams Issues

If your camera or microphone doesn’t work in Teams meetings, the problem is usually an OS permission setting or a driver issue:
  1. Check OS permissions:
    • Windows: Go to Settings > Privacy & security > Camera and make sure Teams is allowed camera access. Repeat for Microphone.
    • Mac: Go to System Settings > Privacy & Security > Camera and Microphone and ensure Microsoft Teams is enabled.
  2. Check Teams device settings: In a Teams meeting or call, click the three-dot menu > Device settings and verify the correct camera and microphone are selected — especially if you have multiple audio/video devices.
  3. Update drivers: Outdated camera or audio drivers can cause recognition failures. On Windows, open Device Manager, right-click your camera and audio devices, and select Update driver.
  4. Restart Teams completely: Right-click the Teams icon in the system tray and select Quit, then reopen Teams and try again.
  5. Test in a browser: Open teams.microsoft.com in Edge or Chrome and join the meeting from the web — if camera and audio work there, the issue is with the desktop app specifically.
Missing notifications from Teams chats, mentions, or meetings can cause you to miss important messages:
  1. Check Teams notification settings: Click the three-dot menu at the top of Teams > Settings > Notifications. Make sure notifications are turned on for chats, mentions, and calls. You can customise which activities trigger a notification.
  2. Check Windows Focus Assist / Do Not Disturb: On Windows, Focus Assist (now called Do Not Disturb on Windows 11) suppresses all notifications. Open Settings > System > Notifications and check if Focus Assist is on, then add Teams to the list of priority apps that can break through.
  3. Check Mac Focus / Do Not Disturb: On Mac, open System Settings > Notifications, find Microsoft Teams, and ensure notifications are allowed. Also check Focus settings to confirm Teams isn’t being silenced.
  4. Re-enable notifications in the OS: In Windows Settings > System > Notifications, confirm that notifications are allowed for Microsoft Teams in the app list.
  5. Check your Teams status: If your status is set to Do Not Disturb, Teams will suppress all notifications. Click your profile picture and set your status to Available.
If you’re unable to join a Teams meeting — whether you see an error, a loading screen that never ends, or simply a blank screen — try these steps:
  1. Try the web version: Go to teams.microsoft.com in your browser, sign in, and find the meeting in your calendar. Click Join — the web version bypasses any issues with the desktop app.
  2. Use the meeting link directly: Click or paste the meeting URL from the calendar invite into your browser — this takes you directly to the meeting without needing to navigate the Teams interface.
  3. Clear the Teams app cache:
    • Windows: Close Teams, then go to %appdata%\Microsoft\Teams in File Explorer and delete the contents of the Cache, GPUCache, and databases folders. Restart Teams.
    • Mac: Close Teams, open Finder > Go > Go to Folder, type ~/Library/Application Support/Microsoft/Teams/, and delete the Cache and databases folders. Restart Teams.
  4. Update Teams: Make sure you’re running the latest version. Click your profile picture in Teams > Check for updates.
  5. Check firewall and antivirus: Security software can block Teams network connections. Temporarily disable your firewall to test, and if that resolves the issue, add Teams to your firewall’s allow list.

​
OneDrive Issues

A red circle with a white X on files or folders in OneDrive indicates a sync error on those specific items. The most common causes are:
  1. File path too long: Windows has a 260-character path limit (unless you’ve enabled long path support). Rename folders or files to use shorter names and move items higher up in your folder structure to reduce the total path length.
  2. Invalid characters in file names: OneDrive doesn’t support certain characters in file or folder names: \ / : * ? " < > |. Rename any files containing these characters and they will sync automatically.
  3. File type blocked: Certain file types (e.g. .tmp, desktop.ini) are not synced by OneDrive by design. This is normal and expected.
  4. Storage full: Check your OneDrive storage at onedrive.live.com — if you’ve reached your quota, files can’t be synced until you free up space or upgrade your plan.
  5. File locked by another app: If a file is open and locked by an application, OneDrive can’t sync it. Close the file in the relevant app and OneDrive will sync it immediately.
Don’t panic — OneDrive keeps deleted files in the Recycle Bin for between 30 and 93 days, depending on your plan and how much storage you’re using:
  1. Go to onedrive.live.com in your browser (or open the OneDrive folder on your desktop and click Recycle bin in the left sidebar).
  2. Find the file or folder you deleted. You can search by name using the search bar.
  3. Right-click the file and select Restore — it will be returned to its original location.
  4. If you also need to restore a previous version of a file that still exists (not deleted), right-click the file in OneDrive online, click Version history, and restore any earlier version.
Business and enterprise plans may have a second-stage SharePoint Recycle Bin that retains items for an additional period after the first-stage bin is cleared — ask your IT admin if you need to recover something from longer ago.

​
Getting More Help

If the steps above haven’t resolved your issue, these resources will connect you with additional support:

Microsoft Support

The official Microsoft support site at support.microsoft.com has thousands of step-by-step articles, troubleshooting wizards, and the option to chat or call with a support agent directly.

Microsoft Community Forums

The Microsoft Community at answers.microsoft.com is an active forum where Microsoft MVPs and support engineers answer questions about every Microsoft 365 app and service.

Support & Recovery Assistant

Download the Microsoft Support and Recovery Assistant from aka.ms/SaRA — it automatically diagnoses and fixes many Office, Outlook, and Teams issues without any manual steps.

Built-In App Help

Press F1 in any Microsoft 365 app or click the ? Help icon in the top-right corner to open the built-in help pane with tutorials, how-to articles, and support options tailored to the app you’re using.