If you see the error message while viewing a claimant's record in back office, it is due to a missing field when the claimant was set up in Core Expense.
If any of the following fields are absent, it indicates that the claimant hasn't been properly configured in the Core Expense module. Please refer to this article on how to setup a new claimant.
To update the fields, this will require a support analyst. Please raise a new case online, reference the title of this article, and provide the following:
Claimant number
Expense group
Input location
Scale Class
Scale Code