Integration fails with not so common error msg

We have a file based data load to FCC system and it has failed with a very strange Error msg:

ERROR [AIF]: The rest service request has failed: 400 - {"status":400,"detail":"The form RestDataGrid_1728017115600 is invalid.","message":"The form RestDataGrid_1728017115600 is invalid.","localizedMessage":"The form RestDataGrid_1728017115600 is invalid."}

Kindly advice!