Error executing enhancement & (function exit &)

What causes this issue?

Component &V2& (function exit, function module) of enhancement &V1& has
been processed. Function module &V2& in function group &V3& was called
for this purpose.
In this function module, an error message was issued in an inadmissible
manner.

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

A message was issued without the addition 'RAISING'.
A message was issued with the addition 'RAISING NAME_EXCEPTION', but the
exception 'NAME_EXCEPTION' is not defined in the interface of the
function module.
The command 'RAISE' was used (i.e. no message set).

System Response

Programming, as described above, leads to an ABEND and is inadmissible.
The ABEND has been intercepted and this message was issued. It is not
possible to continue the processing.

How to fix this error?

Check the programming of function module &V2&, function group &V3&.
Refer to the notes in the documentation on enhancement &V2& on the
subject of the treatment of errors.
As this is a customer-specific enhancement for the system, you should,
if necessary, contact the responsible individual in your company.

Error message extract from SAP system. Copyright SAP SE.