Oh I actually found the reason.
Turns out it was because of the Primary Key form I used for the subform. It was "Replication ID" which is a different type as the RecordID within the Audit table and therefore, has caused the error.
Hi,
thank you for providing this detailed and helpful guide.
After adapting to it, the audit function for the main for works, but for the sub form I get "type mismatch" all the time. Where could the problem be?
Thank you in advance!