Forum Discussion
Debug tools for M Code
Hi RT8
Thank you for reaching out to the Microsoft Fabric Community Forum.
Power Query (M) does not have a traditional debugger, but it provides powerful built-in tools and techniques to debug effectively.
To troubleshoot complex M code:
- Use intermediate steps in the Advanced Editor to inspect outputs step-by-step.
- Apply the try...otherwise expression to catch and isolate errors.
- Use Diagnostics.Trace to log values during execution, especially in recursive or nested functions.
When working with complex or recursive logic:
- Consider using List.Accumulate as a more efficient and readable alternative to recursion, especially for large datasets.
- As suggested by lbendlin , List.Generate can also be a powerful approach for building iterative logic in a controlled manner.
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Thank You!
RT8
Yeah, debugging M code (Power Query language) can be a real pain sometimes.
Unlike normal programming languages where you have fancy debuggers, breakpoints, and step-by-step tools, M code doesn’t really give you much.
👉 Break big stuff into smaller steps.
👉 Add little "peek" columns when things get confusing.
👉 Use Diagnostics.Trace if you really need behind-the-scenes info.
👉 Stay calm — M code is weird but predictable once you slice it into pieces.
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Thannks very much for your suggestions johnbasha33 for your suggestions. I gsest 1 & 4.
Can you please elaborate 2 & 3