# Fixing "The CIL object was not found" in Dynamics AX 2012 > Source: https://netray.co/erp-help/dynamics-ax2012-cil-object-not-found-error > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: ERP Help ## Short answer This error appears when the AOS tries to execute compiled CIL for a class or method that has not actually been regenerated since a code change was imported or edited, so the .NET runtime has nothing matching to run. The fix is a full compile followed by a full CIL generation and an AOS restart, not just a partial or incremental rebuild. ## Kind error ## System dynamics ## Erp Microsoft Dynamics AX 2012 ## Module AOS / CIL compilation ## Query The CIL object was not found. This could be caused by that CIL was not generated - AX 2012 ## Alternate Queries - AX 2012 CIL object not found error - AX 2012 AOS error after code deployment - Dynamics AX 2012 full CIL generation required error ## Applies To Dynamics AX 2012 (R2 and R3), all AOS deployment topologies including multi-AOS environments. ## Steps ### Resolve a CIL-not-found error after a code change **Items:** Confirm the error started right after a code import, model deployment, or manual AOT edit, which is the near-universal trigger. Open Application Explorer and check for compiler error markers on the changed elements before assuming the CIL step is the problem. Run a full compile of the AOT (Application Explorer root > Compile) and resolve any compile errors first; CIL generation cannot succeed cleanly on top of compile errors. Run a full CIL generation, not an incremental one, especially after cross-referenced classes or table methods changed, since incremental generation can miss dependent elements. For scripted or build-server deployments, use axbuild.exe with the xppcompileall and xppcilgenerate/xppcilgenerateall options so both steps run consistently rather than relying on interactive client menus. Restart every AOS instance after CIL generation completes so each one loads the new compiled assembly; a stale secondary AOS in a multi-AOS environment is a common cause of intermittent recurrence. Clear client-side caches and have users restart their AX client sessions after the AOS restart. Verify enough temp disk space was available during CIL generation; a silent partial failure from low disk space can leave some elements uncompiled without an obvious error at the time. ## Sections ### Why AX 2012 has two execution paths **Body:** AX 2012 X++ code can run either interpreted or as compiled CIL executed by the .NET CLR. Compiled execution is faster and is what production AOS instances normally rely on, but it requires an explicit CIL generation step after any X++ change, separate from the AOT compile step that only checks and compiles X++ source. When a class or method has valid X++ source but no matching compiled CIL assembly entry - because CIL generation was skipped, only ran incrementally, or failed partway through - the AOS reports it cannot find the CIL object for that element. ### Why incremental CIL generation misses things **Body:** Incremental CIL generation only recompiles elements it detects as directly changed, which can miss classes or table methods that depend on a changed element through inheritance, event handlers, or cross-references that the incremental scan does not fully traverse in every version. A full CIL generation recompiles everything from a clean state and is the reliable fix once an incremental generation has already been attempted and the error persists. ### Multi-AOS and build automation considerations **Body:** In environments with more than one AOS instance, CIL generation performed through one client session does not automatically propagate a running assembly to every server; each AOS needs to pick up the newly generated CIL, typically via a service restart, which is why the error can appear on one AOS and not another. Teams that deploy code regularly should script compile and CIL generation with axbuild.exe as part of a repeatable build process instead of relying on manual client-menu actions, which reduces the chance of a partial or skipped step. ## Pitfalls - Running only an incremental CIL generation after a significant code change instead of a full generation. - Forgetting to restart every AOS instance in a multi-AOS environment after CIL generation completes. - Ignoring compiler errors on unrelated elements and proceeding straight to CIL generation, which can produce an incomplete assembly. - Running CIL generation with insufficient temp disk space, causing a partial, silent failure. - Deploying a model to production without confirming compile and full CIL generation both completed cleanly in that environment, not just in dev. ## Ai Angle An AI assistant grounded in an AX 2012 environment's deployment history and AOT metadata can flag, for the specific class or method named in the error, that CIL generation has not run since the last import timestamp, and point to whether the mismatch is isolated to one AOS instance - turning a bisecting exercise across compile logs, CIL generation logs, and AOS restarts into a direct root-cause statement. ## Faq ### What is the difference between compiling and generating CIL in AX 2012? **Answer:** Compiling checks and compiles X++ source code within the AOT and reports syntax and reference errors. CIL generation is a separate step that converts the compiled X++ into .NET CIL assemblies that the AOS executes at runtime; both steps are needed for changes to run correctly in compiled mode. ### How long does a full CIL generation take? **Answer:** It depends on environment size and hardware, ranging from tens of minutes to a few hours for large customizations. Because of this, many teams reserve full CIL generation for scheduled maintenance windows or automated build pipelines rather than doing it ad hoc during business hours. ### Can I generate CIL for just one project instead of the whole AOT? **Answer:** The client offers project-level and incremental options, but they carry the risk of missing dependent elements outside the project scope. A full AOT CIL generation is the reliable way to clear this specific error once a targeted attempt has not resolved it. ### Does the AX client also need a restart, or only the AOS? **Answer:** Restart the AOS service(s) first so the new CIL assembly is loaded, then have users close and reopen their AX client sessions, since cached client-side metadata can otherwise continue referencing the prior state. ## Search terms the cil object was not found ax 2012, ax 2012 cil generation error, ax 2012 full cil generation vs incremental, axbuild.exe xppcilgenerate, ax 2012 aos restart after cil generation, dynamics ax 2012 compile error after import, ax 2012 multi aos cil not updated, ax2012 cil object not found fix --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json