HESA Record Validation Check Person.REFUOA2021.2 failed

What causes this issue?

Person.REFUOA2021 must not exist where the staff member does not have an
active contract on 31 July 2020 or Contract.TERMS not equal to 1 or 2 or
(Contract.ACEMPFUN does not = 2 or 3 or (Contract.ACEMPFUN = 2 and
Contract.RESAST = 1))..

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.