Debugging

Lessons in this topic

• Debugging Internal Tables and Field SymbolsDebug internal table reads, loops, field symbols and missing/incorrect row updates.
• Debugging Production Issues SafelyLearn safe production debugging mindset without damaging data or business flow.
• Debugging ABAP like a senior developerBreakpoints vs watchpoints, layers, background debugging with JDBG, checkpoint groups, and short-dump analysis in ST22.
• Session vs External BreakpointsWhen to use each, and how to debug update tasks.
• Watchpoints, Layers and ATCAdvanced techniques for hard-to-catch bugs.
• ST22 Short Dump AnalysisAnalyze ABAP short dumps using ST22 and identify root cause quickly.
• RFC, IDoc and OData External DebuggingDebug ABAP code triggered by external systems, RFC users, IDocs and OData calls.
• Background Job Debugging with SM37 and JDBGLearn how to debug ABAP programs running as background jobs.
• New ABAP Debugger Navigation and Call StackLearn how to move through the new ABAP debugger using step controls, call stack and variable display.
• Update Task DebuggingUnderstand why normal breakpoints do not stop in update task and how to debug update processing.

Interview questions covered

• As an architect, how would you decide, for a new complex integration involving background jobs, RFC calls, and update tasks, what proactive debugging and monitoring hooks should be built into the design from the start, rather than added reactively after production issues appear?
• While debugging a deep call stack involving multiple nested function modules and classes, how do you effectively use the call stack to identify where a wrong value actually originated?
• You are told that a piece of custom code you wrote is 'not running at all' in production, even though it works in the test system. How do you debug why the code is simply not being triggered?
• You are told a custom BAdI implementation is 'not working' for a specific plant, but works fine for others. How do you debug this systematically?
• What is a watchpoint in the ABAP debugger and how is it different from a normal breakpoint?
• A user reports 'No authorization' errors intermittently while running a custom transaction, but they claim their role setup hasn't changed. How do you debug this using SU53 and authorization trace?
• A newly onboarded developer keeps introducing production defects that could have been caught through better debugging discipline before transport. As an architect or technical lead, how would you mentor the team and design a review process to reduce this without slowing down delivery significantly?
• Why is checking sy-subrc after every database operation and sy-tabix inside loops considered a debugging best practice, and what mistakes do junior developers commonly make around them?
• What is system debugging in SAP, and when would you need to use it instead of normal application debugging?
• A SmartForm output is printing an incorrect total amount only for orders with more than one page, while single-page orders print correctly. At a high level, how would you approach debugging this?
• A custom report is taking significantly longer to run for one specific date range compared to others, even though the number of resulting rows is similar. How would you use SAT to root-cause the performance issue?
• An RFC-enabled function module is called from a non-SAP middleware system, and the caller reports a timeout, but no dump appears in ST22 on the SAP side. How would you debug this issue?
• As an architect, how would you design a team-level debugging and diagnostics strategy for a landscape where issues frequently span dialog processing, background jobs, and RFC calls to external middleware, so that root-causing production issues doesn't rely purely on ad-hoc debugging skill?
• What is the difference between an external breakpoint and a session breakpoint in ABAP debugging, and when would you use each in a real project?
• A custom update function module (registered as V1 update) is supposed to insert a record into a Z table on sales order save, but the record never appears. How would you use update debugging to find the cause?
• You suspect a field-symbol is pointing to unexpected or stale data inside a loop, causing wrong values in the output. How would you debug this?
• A user exit is supposed to update a custom field during sales order save, but the field is coming up blank in production. Walk through how you would debug this.
• During an ST05 SQL trace review, you notice the same SELECT statement is executed thousands of times inside a loop, each time hitting the database individually. How would you confirm this root cause and what direction would you recommend for the fix?
• A performance issue in a custom program occurs only in production and only during month-end, but never in the test or quality systems. How would you root-cause this without being able to fully reproduce it outside production?
• How do you set a conditional breakpoint in ABAP, and why is it more useful than a plain breakpoint inside a loop that processes thousands of records?

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