Hi @Derrick Ho ,
Based on my experience, this error could be caused by various reasons and below are some possible troubleshooting steps for reference:
- Restart Outlook: Sometimes, simply restarting the application can help clear up temporary issues.
- Turn off Cached Exchange mode to see if the error persists.
- To eliminate if it's due to any add-ins, run Outlook in safe mode (Close Outlook, Press Win+R, type "outlook /safe", press Enter) and check the result.
- Check for Software Updates: Update Windows and Office/Outlook to ensure no bugs are causing resource leaks.
- Create a new Outlook profile. See relevant sections in Overview of Outlook e-mail profile for information on creating new Outlook profile and switching profiles.
If none of these steps work, consider reinstalling Office.
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