A complex application error has occurred

What causes this issue?

You have attempted to enter data in the system using a BAPI. The system
has discovered that this data is not consistent. Unfortunately, the
exact cause of this inconsistency cannot be determined when BAPIs are
used.

System Response

The system has rejected the data.

How to fix this error?

Please use a dialog transaction to enter the data in the system. You
may then be able to determine the exact cause of the error.

Error message extract from SAP system. Copyright SAP SE.