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PyOCD failed to reset the target


I use the STM32L476 board witch Mbed Studio. I search the debug my program but i have a message error Following:

“pyocd.core.exceptions.TargetSupportError: Target type ‘stm32l476rg’ not recognized. Use ‘pyocd list --targets’ to see currently available target types. See for how to install additional target support.
Could not complete debug: Request reset failed with message: PyOCD failed to reset the target, please check the logs for more information”

What can I do?
Thanks in advance for your answer

I just tried to debug a Nucleo-L152RE using MBED Studio and received a similar message about PyOCD.

Checking the MBED hardware documentation for the L152RE informs me that there three different interfaces supported on USB (and that you can debug)

  • Virtual Com port
  • Mass storage (USB Disk drive) for drag'n'drop programming
  • Debug port

I’ll see what I can learn about PyOCD… and a quick search online gives me a good starting point:


Unfortunately, not all Mbed enabled boards are supported by PyOCD yet. For more info read here.

Best regards, Zoltan

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Zoltan, thanks for that link. That’s really helpful.




You can consider debugging with OpenOCD which supports more targets at the moment than pyOCD. If you cross-compile on Linux then see for example Building and debugging offline with QtCreator.

Best regards, Zoltan

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