Verified on IE 11, Chrome
Environment - Codemap
Login - Partner
Replication Steps:
1)Login with Partner
2)Search and select company
3)Search employee -> go to employee settings -> Change classes
4)Check for the save functionality throwing server error
Expected Result : On-click of save button classes must be saved successfully

Actual Result : On click of save, system throws server error.

Refer attached screen shot and error log