SV521 - Master program & of the user exits does not yet exist.

SAP Error Message - Details

• Message type: E = Error

• Message class: SV - View Maintenance: Customize Messages

• Message number: 521

• Message text: Master program & of the user exits does not yet exist.

What causes this issue?

The master program &V1& of the form routines specified by you is not in
the library.

System Response

The view cluster was not activated.

How to fix this error?

You can create a new program for your form routines directly using ABAP
Editor.
Alternatively, you can go to the program editor using the 'Change'
pushbutton in the program name output field in the 'Event' definition.
If you are trying to access an existing program, check the spelling. You
can change the program name by choosing the 'Choose' pushbutton in the
program name output field in the 'Event' definition.

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

Note:
You must create your form routines in a program of type 'M' (module
pool), 'S' (subroutine pool), or '1' (online program). You cannot define
your form routines in a function group (type 'F'), since the access
mechanism performed on the global data in view cluster maintenance is
not supported in this case.
Include the INCLUDE statement INCLUDE LSVCMCOD in your program to have
access to the global data in view cluster maintenance.

Error message extract from SAP system. Copyright SAP SE.