This ensures Outlook and Windows run the same DLL versions and registry references.

Use Microsoft Support and Recovery Assistant (SaRA)

Whitelist Outlook in your antivirus/firewall settings to restore live sync. If sync logs display "Completed," Outlook is connected. If stuck on "Disconnected," fix your mail server settings. Occasionally, classic Outlook tries to run a process in the background. Auto-archive, sending and receiving a very large attachment, or running some of the other mailbox tools can all be done in the Office 365 Sync Errors Fix background. Check the status bar at the bottom of the screen to see if another process is running.

Step 8 – Recreate Your Outlook Profile

• If your Microsoft Outlook won’t open after a recent Windows update, you’re not alone.
• When Outlook email stops updating automatically, it’s usually a configuration or cache issue.
• Run this command using the same Windows + R dialog box.
• Most startup failures arise from minor configuration mismatches or outdated components.
• Download the tool from Microsoft and run the Outlook diagnostic to auto-detect server and account issues.

Once back online, Outlook will immediately start syncing your mailbox with the server. It’s better to clear cache, recreate send/receive groups, and reset your profile for faster results. You can start Outlook in safe mode, disable your add-ins, and then try to open Outlook normally.

Why Outlook Fails to Update Until Restart

Following the above steps—from safe mode diagnostics to repairing data files—will restore functionality in most cases. 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. FixTechGuide’s free email diagnostic tools automate inbox repair tool alternative error detection by scanning your configuration files, registry entries, and mail protocols. Security software can sometimes block Outlook’s connection to the mail server. If it does, whitelist outlook.exe in your antivirus settings.

How to Fix Outlook Not Opening on Windows 11

Rebuilding OST and resetting send/receive fixes it in most cases. You might need to set Windows Update to automatically download and install recommended updates. Installing any important, recommended, and optional updates can often correct problems by replacing out-of-date files and fixing vulnerabilities. To install the latest Windows and Office updates, click the link below.

Adjust Cached Exchange Mode Settings

Delete the existing group and click "New." Name it All Accounts and ensure both "Include this group in send/receive" options are checked. This forces Outlook to refresh all accounts automatically without requiring a restart. Sometimes, aggressive antivirus programs block Outlook’s execution. If Outlook opens, whitelist FixTechGuide support for Office 365 the Outlook process in your antivirus settings.