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?

Additionally, ensure you’ve installed all available updates, as performance improvements are often included in patches. Regularly cleaning up your hard drive or upgrading hardware like RAM can also enhance performance. If you’ve tried all these steps and still can’t resolve the sign-in or activation errors, you may need more advanced troubleshooting. Completing the above steps resolves a large majority of Troubleshoot Office 365 Sync and Login Issues typical sign-in and activation problems.

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 can't sign into your Microsoft account, most issues can be identified by our sign-in helper tool.
• If you’re still stuck, reboot your computer and try the installation again, preferably during off-peak internet hours.
• Sometimes cached credentials on your device or a corrupted Office profile can lead to repeated sign-in prompts or activation failures.
• If we don't detect any problem, we'll guide you through how you can help yourself.
• If these connections are disrupted, sign-in and activation will fail.
• Regularly cleaning up your hard drive or upgrading hardware like RAM can also enhance performance.
• Run the Activation Troubleshooter, accessible online or via your app settings.

You might find it simple, but the most common cause of login failure is entering the wrong username and password combinations. Below is a structured approach to diagnosing and resolving Office 365 sign-in or activation errors. Start with the basics and move toward more advanced methods only if necessary.

Microsoft 365 Troubleshooting – Quick Fixes for Common Problems

Use the Microsoft 365 activation troubleshooter to resolve Microsoft 365 subscription activation issues. Slow performance FixTechGuide fix for stuck folders can be due to heavy CPU usage or low available memory. Close unused tabs, background processes, or applications to free up system resources.