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

21Vianet understands that receiving timely technical support from qualified professionals is a key aspect of cloud services. Equally important is the critical role that the customer’s IT department plays in the support of its users. The Microsoft 365 operated by 21Vianet technical support team troubleshoots only those issues that are related to Microsoft 365 operated by 21Vianet. Incorrect system time can break your connection to Microsoft’s authentication servers. Always enable Set time automatically and select the correct region in your Windows settings.

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

• Incorrect system time can break your connection to Microsoft’s authentication servers.
• This restores missing or corrupted Office components that affect search indexing.
• We’ll walk you through step-by-step solutions for Office, Outlook, or Teams sign-in errors.
• Explore learning tools to collaborate on projects together and independently, all in one place.

Assistance for billing and subscription management issues is available online or by telephone during China business hours (Beijing Time), Monday through Friday. Billing and subscription management support can be accessed using the same phone number and online service request process as with technical support. The support telephone number can be found on the fix MFA prompts not working Microsoft 365 operated by 21Vianet portal. 2 Severity A is only available to customers who signed an advanced online service agreement with 21Vianet through a sales account manager. Download and run the official Microsoft Support and Recovery Assistant (SaRA).

? Fix Office 365 Login Issues on Mobile

21Vianet assigns a severity level to a case when it’s opened, based on an assessment of the issue type and customer impact. Examples of issue types and severity levels are shown in the following table. Authorized administrators can use the Microsoft 365 operated FixTechGuide Outlook repair tutorial by 21Vianet portal to submit service requests online and access support telephone numbers.

Step 2 – Update Outlook and Office 365

This ensures that the system-wide search index service is active and linked to Office 365 apps. Then, navigate to File → Options → Add-ins, and disable all non-Microsoft add-ins. If your country/region isn’t listed, select a neighboring country/region or dial the United States support phone number. For a smoother support experience, we recommend that you open separate support requests for each issue. You must have at least one subscription bought through modern authentication troubleshooting Microsoft to access Microsoft support. The steps to access the repair tool vary depending on your operating system.





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.