[OUTLOOK] - Conflict Message

To fix, do the following:

1.       Open the Calendar pane in Outlook, and right-click the Calendar folder.

2.       Select Properties.

3.       On the General tab, select Clear Offline Items.

4.       Select OK.

It will look like all of your calendar appointments will have disappeared. Close all Outlook windows and restart the app. The appointments should re-appear and the conflict messages will have disappeared.

 

Reference:

Outlook shows conflict errors when updating or cancelling meetings - Microsoft Support

Calendar reminders in Outlook can't be dismissed or keep reappearing - Exchange | Microsoft Learn