TSR Integration->Classes & Payroll->Server error is displaying while assigning class to employee added from Bullhorn to Workterra.

1] Add a employee to Workterra through Bullhorn API..
2] Login to the application as a partner.
3] Navigate to "Assign Classes and Payroll Schedule"
4] Search newly added employee and try to assign class.

Actual Result:
Class get assign but server error is displaying.
Expected Result:
Server error should not be display.
Refer attached screenshot and error log for more details.

Cc: Saurabh Sablaka, Prasad Pise, Sushodhan Vaishampayan