Calendar is saying "The server responded with an error."
The calendar on my Macbook Pro keeps popping up a graphic that states that "the server responded with an error." I have the option to 1. Revert to Server 2. Try Again or 3. Ignore. It takes several attempts at clicking "Ignore" to get the graphic to go away. The other two options just bring up the graphic again.
Any idea on how to fix this?
MacBook Pro 13″, macOS 11.7