Part appraisal(s) still being processed

What causes this issue?

One or more appraisal documents have not yet been completed.
When you complete these appraisal documents, the system also completes
all part appraisals.

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.