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µVISION DEBUGGER: "Command not supported" error using ST-Link debugger

Information in this knowledgebase article applies to:

  • MDK v5.29 and later versions
  • ST-Link debug adapter


I'm working on a STM32 MCU device with an on-board ST-Link v1.x debugger. After upgrading to MDK v5.29, I can neither program the flash nor start a debug session, in which cases µVision shows the following error:

Command not supported
Error: Flash Download failed - Target DLL has been cancelled

How can I resolve this issue?


MDK v5.29 ships with an updated ST-Link debug driver DLL from ST which adds support for CMSIS debug sequences and other new features. This addition required changes to the ST-Link firmware which are available in the v2.x and v3.x variants of the debugger. At this moment it is not planned to roll out similar changes to the ST-Link v1.x variant.


In order to resolve this issue, download the previous version MDK v5.28a and copy the following debugger driver DLL file from the installation folder of MDK v5.28a to the corresponding folder of MDK v5.29


In this case MDK v5.29 can use the older debugger driver DLL from MDK v5.28a to work with ST-Link v1.x debugger.


ST-Link v2.x and v3.x debuggers are not affected by this. If you get the same error while using ST-Link v2.x or v3.x debugger, upgrading the firmware of your ST-Link debugger to the latest version can resolve the issue.

Last Reviewed: Monday, May 25, 2020

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