Hi, FresTea~
Good day!
Thank you for posting to Microsoft Community. We are happy to help you.
According to your description, the issue of your concern that there's a prompted error displays on your Outlook desktop client.
For narrowing down this issue, please be kindly to check if there's a same issue under the Safe mode - Open Office apps in safe mode on a Windows PC.
If it works well under the safe mode, please give an attempt for Repair an Office application and see if it helps.
In addition, please give it a shot by creating a new profile - Create an Outlook profile and check if it can make any differences.
We're glad to help you and looking forward to your new updates.
Sincerely,
Alex | Microsoft Community Moderator.