Application code &1 for &2 does not exist

What causes this issue?

You have entered an application code that does not exist.

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

System Response

How to fix this error?

Enter a valid application code. You can define new application codes in
Customizing.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.