9 ABAP mistakes AI coding assistants keep making (and how to prevent them)

Posted on Oct 27 • Originally published at abapforagents.com

AI coding assistants are great at languages with millions of public examples. ABAP isn't one of them, and it trips them up in two specific ways:

The result is a small set of mistakes that come back again and again, whether you use Cursor, Claude Code or GitHub Copilot. Here are nine of them, with the fix for each.

The assistant doesn't know which system you're on, so it writes the newest syntax it has seen. Some availability dates worth knowing (from SAP's ABAP Keyword Documentation release notes):

ECC 6.0 runs on SAP_BASIS 7.50 at most (EHP8), so x += 1. won't compile there, and neither will a view entity. On 7.40 SP05 to SP07, this is a syntax error:

SELECT vbeln, erdat FROM vbak WHERE erdat >= @ date_from INTO TABLE @ DATA ( orders ). " needs 7.40 SP08 Enter fullscreen mode Exit fullscreen mode The SP05-safe version declares the target first:

TYPES: BEGIN OF ty_order, vbeln TYPE vbak - vbeln, erdat TYPE vbak - erdat, END OF ty_order. DATA orders TYPE STANDARD TABLE OF ty_order WITH EMPTY KEY. SELECT vbeln, erdat FROM vbak INTO TABLE @ orders WHERE erdat >= @ date_from. Enter fullscreen mode Exit fullscreen mode Prevention: give the assistant three facts before it writes a line: language version (ABAP for Cloud Development or Standard ABAP), product (S/4HANA or ECC) and release. If you can't, tell it to assume the lowest plausible release and never mix syntax from different releases in one answer.

This one activates fine and passes a quick test, which is why it's dangerous. If the internal table after FOR ALL ENTRIES IN is empty, the whole WHERE clause is ignored and every row of the database table is read.

IF keys IS NOT INITIAL. SELECT vbeln, erdat FROM vbak FOR ALL ENTRIES IN @ keys WHERE vbeln = @ keys - vbeln INTO TABLE @ DATA ( orders ). ENDIF. Enter fullscreen mode Exit fullscreen mode FOR ALL ENTRIES also removes duplicate result rows, so select all key fields or you lose data silently. There's a full walkthrough in FOR ALL ENTRIES with an empty table.

Z_GET_ORDER_STATUS, I_SomethingView, BAPI_WHATEVER: invented names follow SAP's naming conventions, so they read as real. A model will also invent parameter names for function modules that do exist.

Prevention: require the assistant to name every SAP object it relies on and to flag the ones it isn't sure about. Then check them yourself: "Open ABAP Development Object" in ADT, SE37/SE24/SE11 in SAP GUI, or SAP's Cloudification Repository for the release state. In ABAP Cloud only released objects are allowed, and an I_ prefix is not proof of either existence or release.

Models trained on classic READ TABLE code write this:

DATA ( item ) = items [ id = key ]. IF sy - subrc <> 0. " never reached on a miss... ENDIF. Enter fullscreen mode Exit fullscreen mode A table expression doesn't set sy-subrc. If the line isn't found it raises CX_SY_ITAB_LINE_NOT_FOUND, and without a TRY block the program dumps. Use one of these instead:

IF line_exists ( items [ id = key ] ).... ENDIF. " 7.40 SP08+: initial value instead of an exception item = VALUE # ( items [ id = key ] OPTIONAL ). Enter fullscreen mode Exit fullscreen mode (The exception: ASSIGN items[ id = key ] TO <item>. does set sy-subrc and raises nothing.)

ABAP looks enough like other languages for the model to slip:

IF a!= b. " wrong: ABAP uses <> i ++. " wrong: no ++ operator s = "text". " wrong: " starts a comment Enter fullscreen mode Exit fullscreen mode The correct forms are IF a <> b., i = i + 1. (or i += 1. from 7.54) and s = `text`. with backquotes or single quotes. There is no null either: use IS INITIAL or IS NOT BOUND. And RETURN value. only exists in functional methods from 7.58 (ABAP Cloud 2211); below that, assign the returning parameter and then RETURN.

boolc( ) returns a string, not abap_bool, which can surprise you in comparisons. xsdbool( ) returns type c length 1 and works with abap_true / abap_false:

DATA ( is_late ) = xsdbool ( due_date < today ). IF is_late = abap_true.... ENDIF. Enter fullscreen mode Exit fullscreen mode 7. Classic ABAP inside ABAP Cloud In ABAP for Cloud Development, sy-datum, WRITE, SUBMIT, CALL TRANSACTION, direct reads of SAP tables like VBAK and non-released function modules are not allowed. Assistants reach for them first because that's what most public ABAP looks like. For the date, use the released class:

DATA ( today ) = cl_abap_context_info => get_system_date ( ). " UTC Enter fullscreen mode Exit fullscreen mode That returns the system date in UTC. For the user's local date, SAP points to the XCO library with the user time zone.

In the ABAP RESTful Application Programming Model (RAP), the framework owns the logical unit of work. COMMIT WORK, ROLLBACK WORK, COMMIT ENTITIES and ROLLBACK ENTITIES don't belong in behavior handler or saver methods. Errors go back through the failed and reported structures, not through MESSAGE or exceptions. Many classic BAPIs commit internally, so they must not be called in the interaction phase either.

BAPIs don't raise exceptions or set sy-subrc for business errors. They fill a RETURN table, so read it:

DATA return TYPE STANDARD TABLE OF bapiret2 WITH EMPTY KEY. "... call the BAPI, passing return... IF line_exists ( return [ type = 'E' ] ) OR line_exists ( return [ type = 'A' ] ). " handle the error, do not commit ENDIF. Enter fullscreen mode Exit fullscreen mode Commit separately with BAPI_TRANSACTION_COMMIT, and not once per record inside a loop.

You can paste these reminders into every prompt, but it's easier to put them in the file your tool reads automatically:

Keep these files short. Every always-on line costs context, and long instruction files are followed less reliably. A good rules file states the target release, forbids invented objects, lists the traps above and ends with a self-check the assistant runs before answering.

Rules are guidance, not enforcement. The assistant can still ignore them, so keep the syntax check, ATC and ABAP Unit as your gate, and run them on everything AI-generated before it reaches a transport.

Free MIT-licensed ABAP rules for Cursor, Claude Code and Copilot are on GitHub, and there are more guides at abapforagents.com/guides.