Diagnosis
You deleted the vendor's assignment test group.

System Response
During the next assignment test run, all invoices for this vendor thatwere already in the assignment test will be set to Error inAssignment Test because no assignment test group will be found forthese invoices.
The assignment test group is not saved in the invoice; instead, it isread from the vendor master during each assignment test run.

Procedure
Check the settings and adjust them as necessary.