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 rebuild Outlook data file quickly 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 we don't detect any problem, we'll guide you through how you can help yourself. Being a Microsoft 365 user, if you have encountered an error while logging into your account, you are not alone. Remember, if all else fails, reaching out to Microsoft Support directly or using their official support documentation can provide tailored assistance for complex organizational setups. With the right planning and knowledge, nearly all sign-in and activation troubles can be resolved quickly and efficiently. Sometimes cached credentials on your device or a corrupted Office profile can lead Outlook Not Sending or Receiving Email to repeated sign-in prompts or activation failures.

Recover your account

Office 365 uses several internet endpoints and cloud services to authenticate users and validate licenses. If these connections are disrupted, sign-in and activation will fail. Use the Excel check troubleshooter to resolve Excel for Windows startup, hang, or crash issues. Get Help has troubleshooters for Microsoft 365 you can run for many common scenarios. These often help resolve issues without the need to contact support. If a troubleshooter is available for your issue, select Start to run that troubleshooter.

3 Step 3: Verify Network Connectivity and Firewall Settings

• Double-check your internet connection, as OneDrive requires an active network to sync files properly.
• Use the Microsoft 365 shared computer activation (SCA) troubleshooter to enable shared computer activation for Microsoft 365 applications.
• You'll have the option to do that on your \"My Questions\" page if you choose to rate our interaction or you can request me by name if you wish.
• If you would like to ask me another question in the future, you can add me as a favorite Expert.
• Keep cache sizes clear and refer to official Microsoft troubleshooting manuals for persistent app freezes.
• For manual uninstallation, delete leftover Office files in Program Files or Library folders, and clear Microsoft credentials from your system to ensure a clean reinstall if required.

Follow this guide to ensure a smooth and error-free Microsoft 365 login experience. Additionally, check out the above-listed security best practices and keep your team members aware of common troubleshooting tips. Troubleshooting Microsoft 365 login issues often requires a methodical approach, starting with basic checks and escalating to more complex troubleshooting if needed. Remember, proactive management and regular reviews of your IT infrastructure can prevent many common issues, keeping your business operations running smoothly. Make sure your phone’s operating system is supported by Microsoft 365.

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 Fix Outlook and Office 365 Errors 2025 once a connection is re-established.