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.
• For iPhone users, reinstalling Outlook or updating to the latest iOS often resolves stuck sign-in loops instantly.
• 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.
• This resets your authentication cache and forces a fresh token request.

For iPhone users, reinstalling Outlook or updating to the latest iOS often resolves stuck sign-in loops instantly. Many users have both personal Microsoft accounts (e.g., Exchange connectivity diagnostic Outlook.com) and work/school Office 365 accounts. If both are signed in simultaneously, the system can confuse the authentication path.

? 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 disable faulty add-ins in Outlook corruption issues. Partial updates often break compatibility between Windows libraries and Office binaries.

Step 2 – Update Outlook and Office 365

We provide instant guidance for update errors, installation failures, inbox repair tool alternative and Office activation issues. When Office 365 search stops working after updates, it’s usually a minor indexing or cache issue — not a major fault. Following the steps above should restore your search functionality quickly. For advanced troubleshooting, FixTechGuide offers remote support to restore performance and indexing accuracy for Outlook and other Office apps. Microsoft 365 crashes after updates can be frustrating, but these fixes will restore stability quickly.





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.