Invalid pointer operation on appointment

Hello,

our customer has the Version 2018 R2.

If the user get's an appointment from a customer via Exchange-Server. The user can't edit the company or/and person or/and info.

The error is:

Es trat ein unerwartetes Ereignis auf: EInvalidPointer: Invalid pointer operation

The system-log: Creating stack-trace ID:358592336. Error message is "Invalid pointer operation"

Hope to get help soon.

Thank you.