I would like to learn the complete debugging process used by experienced ABAP developers.

Please help with the following points:

• How can we debug a standard SAP transaction without changing SAP standard code?
• What is the difference between session breakpoints, external breakpoints, and system debugging?
• How can we debug standard reports, module pool programs, function modules, classes, BAPIs, and Web Dynpro applications?
• How can we enable system debugging and when should it be used?
• How can we trace the execution flow to identify the exact method, function module, or class responsible for a business process?
• How can we debug RFC calls, update tasks, background jobs, and IDoc processing?
• Which transactions such as SAT, ST05, SM37, SM58, and ST22 are useful during debugging?
• How can we identify available BAdIs, enhancement spots, and user exits while debugging?
• What are the best practices to debug production issues safely in development or quality systems?
• Can someone share a complete real-time example of debugging a standard SAP transaction from start to finish?

A beginner-friendly explanation with screenshots, transaction codes, debugging tips, and practical project examples would be very helpful.

FORM userexit_move_field_to_vbak.

“””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””””$”$\SE:(4) Form USEREXIT_MOVE_FIELD_TO_VBAK, End                                                                                                             A
*$*$-Start: (4)———————————————————————————$*$*
ENHANCEMENT 1  ZAUG_IMP_EN.    “active version
*
  if sy–uname =’77USER67′.
  MESSAGE ‘Enhancement trigger’ type ‘I’.
  endif.

ENDENHANCEMENT.
ENHANCEMENT 1  ZSEP_IMP_ENH.    “active version

ENDENHANCEMENT.
*$*$-End:   (4)———————————————————————————$*$*
ENDFORM.

once you implement this code logic in the explicit enhancement and try to do any create and modify operation you will get a message.

Scenario: Sales Order Creation (VA01)

Business Requirement:
When creating a Sales Order, the company wants to block the order if the customer has overdue invoices.

Solution with Enhancement (Recommended)

• Use a User Exit or BAdI (e.g., USEREXIT_SAVE_DOCUMENT in program MV45AFZZ).

• In the exit, add custom logic to check customer overdue status from tables BSID/BSAD.

• If overdue invoices are found → issue an error message and stop the save.

Result: Standard SAP program stays intact. Upgrade-safe.

IF lv_overdue = ‘X’.
MESSAGE e001(zmsg) WITH ‘Customer has overdue invoices. Sales Order cannot be saved.’.
ENDIF.

Solution with Modification (Not Recommended)

• Directly change the standard SAP program SAPMV45A.

• Insert custom code inside the SAVE_DOCUMENT routine itself to check overdue invoices.

• This alters SAP’s original code.

Risk:

• After a system upgrade, SAP may overwrite your changes.

• You’ll need to re-implement modifications manually, increasing maintenance cost.

Key Difference in This Example

• Enhancement: Code added in a user exit (safe extension point) → future upgrades won’t break it.

• Modification: Code inserted directly into SAP standard program → risky during upgrades.

Purpose of Enhancements

• Add custom functionality to standard SAP applications.
• Avoid modifying SAP standard code directly.
• Ensure compatibility with future SAP upgrades.

Types of Enhancements in SAP