Form name "&1" is invalid

IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.

What causes this issue?

An invalid form was entered in Customizing. As a result, the
corresponding form cannot be printed.

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?

Inform your system administrator.

Procedure for System Administrators

The form name that was entered in Customizing ("&V1&") is invalid. Use
the <DS:SIMG.SIMG_CFMENUOLSDFORM>Define forms and print programs</>
activity to correct the form name in Customizing.
ENDIF.

Error message extract from SAP system. Copyright SAP SE.