Arm Mbed OS support forum

Can't debug Nucleo L432KC (supported board)

I can’t debug my L432KC in Mbed Studio. I can debug it with CubeIDE and it is also in the list of supported boards for debugging. In Mbed Studio the USB-Symbol is yellow and I can’t use the debug button.
I tried to upgrade the ST-Link firmware and the ST-Link USB driver, but it didn’t help.

Any suggestions on how to fix this?



just for clarification. Do you have the Mbed Studio and its modules updated?

I have the USB-symbol green and I can press the debug button but after the session start, it is ended immediately.

My setup:
MbedStudio 1.3 on Windows10 (St-link firmware V2J37M26).

  • Nucleo-L432KC - description above - “…exit code 1”
  • Disco-F746NG - “No cores were discovered!”
  • Nucleo-F767ZI - working

@arekzaluski any recommendation?

BR, Jan

Hi Jan,

just for clarification. Do you have the Mbed Studio and its modules updated?

I’m also running Mbed Studio 1.3 on Windows 10 and the ST-LinkUpgrade tool tells me that my firmware version is V2.J37.M26.


Hi Stefan,

Apologies, the L432KC was mistakenly marked as supported with debug capabilities on the website. We will update this information now.



the target is still marked as supported - platform tree.

BR, Jan

Looks like it’s been 15 days, and it still shows up on the mbed development boards page after adding a filtering for “Debug”. I’m glad to know, though.


I just created a Pull Request to add this nucleo IC to pyocd here:

With this, I can debug manually from the command line or from vscode.

Would you mind checking how can we get this on mbed studio?

Best regards,
Wagner Sartori Junior

The debugger works fine with Nucleo L432KC using the STM32 IDE, but it doesnt work with pyOCD which is used by MBED Studio.
thats very annoying …

That’s the reason I sent the PR. The PR is now merged into master, not sure when there’ll be a new release.

I made it to work here on mbed studio. You’ll have to git clone pyocd master, than depending on your os, on a Mac, /Library/Application Support/Mbed Studio/mbed-studio-tools/python/. you can /Library/Application Support/Mbed Studio/mbed-studio-tools/python/bin/pip install [your_pyocd_cloned_directory].

After that, go on mbed studio target, click on the IC chip icon, select cortex-m and change the --target from cortex-m to stm32l432kc.

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Thanks, but anyhow, i managed to compile mbed-os-v5.14 with the STM32 IDE and prefer to use the STM environment over the mbed-Studio.