Break points for debugging custom API services are not working

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Posted on by D365FO Junior-Dev

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I've created a custom API service using X++ in D365 F&O I could post JSON payload from Postman to the API endpoints successfully I set breakpoints for the code of the service api class method but the breakpoints aren't working didn't hit when I send a JSON payload from Postman. Some guides suggest attaching to w3wp.exe
for debugging

What I done so far:

1- The custom service API is now exist under Services the AOT
2- I set breakpoints inside the code of method
3- I open the usconeboxax1aos.cloud.onebox.dynamics.com from IIS

The break point is display this warning message ( The breakpoint will not currently be hit. No symbols have been loaded for this document).

can you show me the right way to debug the custom api service in Visual Studio ?

Thanks

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Mohamed Amine Mahmoudi 26,801 Super User 2026 Season 1 on at

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Hi,

to debug a custom API you must attach to Batch.exe process.

please refer to this : https://community.dynamics.com/blogs/post/?postid=2cf46b26-ca5b-4c56-bc45-e85538482be1

Best regards,

Mohamed Amine MAHMOUDI

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Waed Ayyad 9,089 Super User 2026 Season 1 on at

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Hi,

Check if your model is added to the models that are included in the debugging, to check it go to Extensions Menu -- Dynamics 365 --Options --- Dynamics 365 --- Debugging --- Check if your model is checked or not.

Thanks,
Waed Ayyad
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Waed Ayyad 9,089 Super User 2026 Season 1 on at

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Hi,

Check if your model is added to the models that are included in the debugging, to check it go to Extensions Menu -- Dynamics 365 --Options --- Dynamics 365 --- Debugging --- Check if your model is checked or not.

Thanks,
Waed Ayyad
If this helped, please mark it as "Verified" for others facing the same issue

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Layan Jwei 8,165 Super User 2026 Season 1 on at

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Hi,

if you go to:
Extensions - Dynamics 365 - Options then Dynamics 365 - Debugging
Then you have two options:
1. It's either, you untick the tick box near the red arrow, where it will include all modules to debug from
2. you tick the tickBox in red, then you choose the modules u need near the blue arrow and tick their boxes (For example: your model, application suite...etc)and make sure the element you want to debug is inside your project

option 2 is more preferred for performance.

Then you can Debug via IIS express when you click "Attach to process" and it should work (no need for batch)

Also make sure you put your break point at the beginning of the service, to make sure that it's not being hit because of code.

Thanks,
Layan Jweihan
Please mark this answer as "Verified" if it solved your issue. In order to help others who will face a similar issue in the future

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Martin Dráb 239,036 Most Valuable Professional on at

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To summarize it (and correct some wrong information), you must attach debugger to the process running the code that you want to debug. Typically it's IIS Express (iisexpress.exe), but it may also be IIS (w3wp.exe).

It would be Batch.exe if you debugged a batch job, but it's not your case.

Note that you can even attach the debugger to several processes, if you aren't sure which is the right one.

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Waed Ayyad 9,089 Super User 2026 Season 1 on at

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Hi,

Is your issue resolved? If yes, mark the answers that helped you as verified.

Thanks
Waed Ayyad

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Waed Ayyad 9,089 Super User 2026 Season 1 on at

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Hi,

Is your issue resolved? If yes, mark the answers that helped you as verified.

Thanks
Waed Ayyad

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Waed Ayyad 9,089 Super User 2026 Season 1 on at

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Hi,

Is your issue resolved? If yes, mark the answers that helped you as verified.

Thanks
Waed Ayyad

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