Troubleshooting activity '&1' can not be started

What causes this issue?

The troubleshooting activity '&V1&' can only be started after succesful
execution of standard generator.

System Response

Process will be canceled.

How to fix this error?

Start the creation of programs by executing the activity from the
process tree.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.