Hi Susritha,
It seems that you had performed association or disassociation operation between the target knowledgearticle entity and another entity.(1:N or N:N)
e.g:
I have a contact, and I removed him from a specific marketing list, then system will create a new event record called "Remove Members" in related audit history records.

Before the record is created, the web api was able to execute successfully, however, after creation of record, I encountered same error as yours.
Please remove any association or disassociation audit records of the target record, or take a record which only has CRUD operations to test the api again.
Regards,
Clofly