Problem: you want to debug BDOC processing in CRM, executed from SMQ2 TCODE.

Solution: First of all you need to enable „System” and „In Update Task debugging”. See post: [cref how-to-enable-system-andor-in-update-task-debugging].

Second step will be to put external breakpoint in the FM that will process the BDOC. Important thing here is, that this breakpoint should be activated for RFCUSER (or any other user that the FM will run on).

When you are done with step 1. and 2. go to SMQ2 and reprocess the BDOC. System will stop in the place where you put the breakpoint.