Setting a breakpoint at a Function Module / Root cause analysis
When a transaction is executed for example FPY1 for payment runs, an event associated with the specified Function Module is called.
If for instance an error occurs during the run, setting a breakpoint at the Function Module would be the best way to determine the root cause of the error.
1. Run transaction FPY1
2. If an error occurs during the run, start the debugger using /h
3. In debug mode, on the top menu select "Set Breakpoint at Function Module"
4. Enter the relevant Function Module associated with the payment run event
5. Single step into the code up to the point where the program run is initiated
6. Press shortcut key (F8) to point to the given Function Module
7. Special emphasis should be placed on the IF Conditions set within the FM, as well as the conditions when the sy-subrc=0
8. Once a condition when sy-subrc=0 becomes void, an error/warning will trigger in the system.
Hint: To search for an event associated with a particular transaction, please use transaction FQEVENTS. Double-clicking this event will highlight the associated Function Module.