User exit form pool & does not exist

What causes this issue?

The user exit formpool &V1& is not available. A possible reason is, for
example, because of the system transport of validations and/or
substitutions. Formpools for user exits cannot be copied across
systems.

System Response

The coding for the call up of the user exit is not generated and/or the
the condition check contains a syntax error.

How to fix this error?

Create the formpool for the user exit. You can find information on how
to do so under <DS:DE.EX_PROG>User exit formpools</>.

Error message extract from SAP system. Copyright SAP SE.