Breakpoints for user &1 must exist to debug this background job.

What causes this issue?

You try to activate debugging for a background job using stand-alone
SAPGui. To do so, you need to have at least one breakpoint set in the
current logon session for the user the relevant job step is executed
for.
This is currently not the case.

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?

Go to the ABAP Editor and ensure that the debugger activation is set for
the correct user without any further limitations (e.g. to the current
application server). Use menu:
Utilities -> Settings, ABAP Editor -> Debugging.
Then set an external breakpoint at the relevant position.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.