Cannot calculate work in process at target costs

What causes this issue?

The <DS:GLOS.WIP_calculation>WIP calculation</> process could not
determine any <DS:GLOS.work_in_process>work in process</> due to an
error in the application.

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?

Look at the previous messages to determine the cause of the error.

Error message extract from SAP system. Copyright SAP SE.