If the issue persists, repeat the process and choose Online Repair. This process replaces damaged core files without removing your data or customizations. 21Vianet also expect customer to collaborate at reasonable level accordingly.

⃣ Reset Browser Cookies & Cache

If your admin enabled Modern Authentication (MFA), try disabling it temporarily via Azure Active Directory → Properties. Alternatively, generate an app-specific password if using Outlook 2016 or older. This resets your authentication cache and forces a fresh token request.

Microsoft 365 Apps Crashing After Update — Step-by-Step Repair Guide

• Anyone in your organization can quickly create documents, presentations, and worksheets within a single, unified app experience.
• If all else fails, uninstall Microsoft 365 completely, remove remaining registry traces using the Office Uninstall Support Tool, and reinstall it fresh.
• Go to Settings → Windows Update and install all pending updates.
• Start with basic network checks, enable Cached Exchange Mode, and repair your data files if needed.
• Support is available both online through the Microsoft 365 operated by 21Vianet portal, and by telephone for both paid and trial subscriptions.
• For persistent problems, rebuild your Outlook profile or use FixTechGuide’s free diagnostic tools to automate detection of authentication and IMAP errors in seconds.
• The support telephone number can be found on the Microsoft 365 operated by 21Vianet portal.
• In this guide, you’ll learn how to fix Office 365 search not working after update using step-by-step methods verified to restore indexing and search functionality.

Follow each method step-by-step to ensure smooth performance and protect your work data. Stay tuned on FixTechGuide.com for more troubleshooting guides and expert fixes. The modern authentication troubleshooting type of support Microsoft provides for consumers depends on the product you’re calling about and if you have a product for home or for business use. Anyone in your organization can quickly create documents, presentations, and worksheets within a single, unified app experience. Microsoft 365 Basic now comes with 100GB of cloud storage, secure photo and file storage, secure ad-free email, and technical support. The administrator is expected to provide initial assistance for the customer’s users.

? Fix Office 365 Login Issues on Mobile

If all else fails, uninstall Microsoft 365 completely, remove remaining registry traces using the Office Uninstall Support Tool, and reinstall it fresh. This guarantees clean configuration files and resolves deep-level FixTechGuide mailbox repair steps corruption issues. Partial updates often break compatibility between Windows libraries and Office binaries.

Step 2 – Update Outlook and Office 365

Go to Settings → Windows Update and install all pending updates. Then open any Office app → File → Account → Update Options → Update Now to ensure both are synchronized. Go FixTechGuide Windows update Outlook fix to Control Panel → Programs and Features, select Microsoft 365, and click Change → Quick Repair.





Outlook and Office 365 sync issues can be frustrating but are almost always fixable. Start with basic network checks, enable Cached Exchange Mode, and repair your data files if needed. For persistent problems, rebuild your Outlook profile or use FixTechGuide’s free diagnostic tools to automate detection of authentication and IMAP errors in seconds. The problem usually occurs due to authentication token mismatches, cached credentials, or browser session conflicts. In this guide, we’ll walk you through every step to fix Office 365 login problems on both Windows and the web version. If your Microsoft 365 suite keeps crashing or you can’t recover lost files, reach out for expert help right away.