Functional area was changed from &1 to &2

What causes this issue?

Before calling the account assignment derivation, the line item
contained functional area &V1&. The account assignment derivation has
derived functional area &V2& instead.

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.