Go to any Office app and ensure you’re signed in with the same Microsoft account linked to your license. Remove and re-add your account under the "Account" settings of the app if needed. If this doesn’t work, reset the credentials in your Windows Credential Manager online Outlook email repair utility or contact Microsoft support for further assistance. Despite its robust feature set and user-friendly design, it’s not uncommon for end users and IT professionals to encounter sign-in and activation issues. If you or your employees can’t sign in to Office 365, or if the applications repeatedly prompt for activation, productivity can grind to a halt. Yes, Microsoft 365 works offline for most apps like Word and Excel.

How do I fix the ‘Product Activation Failed’ error in Microsoft 365?

If you’re unable to sign in to your Microsoft 365 account, ensure you’re using the correct email and password. Locked accounts, due to multiple failed attempts, may require waiting or following unlock instructions. Check your internet connection, as weak connectivity can cause issues. For work or school accounts, confirm with your organization that your account is active. Browser or app issues, like outdated software or cached data, can also interfere; try clearing your cache or switching clear Outlook credentials manager browsers. Troubleshooting Office 365 sign-in or activation issues can be straightforward if you approach the problem methodically.

Recover your account

Use the uninstall troubleshooter to uninstall Microsoft 365, Office 2021, Office 2019, or Office 2016 from your Windows PC. Find solutions to common problems or get help from a support agent.

3 Step 3: Verify Network Connectivity and Firewall Settings

• If you or your employees can’t sign in to Office 365, or if the applications repeatedly prompt for activation, productivity can grind to a halt.
• Use the Microsoft 365 setup troubleshooter to install Microsoft 365, Office 2021, Office 2019, or Office 2016 on your Windows PC.
• For syncing or email issues, verify your mobile connection or switch between WiFi and cellular data.
• Slow performance can be due to heavy CPU usage or low available memory.
• If your account is locked due to multiple unsuccessful login attempts, wait for the lockout period to end.
• In many cases, performing simple checks—like verifying correct usernames and valid licensing—will resolve the issue quickly.

Regardless of the root cause, understanding the core steps to troubleshoot and resolve these issues is essential for an efficient, well-run IT environment. A slow installation is often caused by network problems or background tasks monopolizing bandwidth. Close other programs or downloads running on your device to free up resources. If you’re still stuck, reboot your computer and try the installation again, preferably during off-peak internet hours. If network connectivity is solid and you’ve ruled out firewall or proxy blocks, clearing cached credentials and repairing the Office installation are the next logical steps. After running the tool, restart your system to clear any residual files.

Microsoft 365 Troubleshooting – Quick Fixes for Common Problems

Simply open the Office app normally, and all your files are saved locally until internet access resumes. For cloud-based services like Outlook or OneDrive, offline access won’t work until you sync online again. Make sure to save any updates for immediate syncing FixTechGuide fix for stuck folders once a connection is re-established.