Arduino UNO Debugging Fails

Running into an issue debugging an Arduino UNO. I have a Leonardo and can debug it without issue. I setup the most basic of sketches and the debugger on the UNO either just sits with the debug taskbar visible and doesn’t hit any breakpoints. I forced the upload, monitor and debug ports in the platform.ini without any success. The board details in the documentation indicates debugging is fully supported without any external probes.

I have confirmed I have the latest version of

Any suggestions?

Forgot to include the platformio.ini details (debug is commented out as it didn’t seem to make a difference);

platform = atmelavr
board = uno
framework = arduino
upload_port = COM3
monitor_port = COM3
; debug_port = COM3


Yes because PlatformIO supports a simulator program (simavr) and avr-stub, which runs a GDB server on the device if you include a special library and a piece of code.

Please further fully read the documentation of each debugging tool that is stated there.

If you want to use the simulator, as per linked docs, add debug_tool = simavr. Otherwise follow the tutorial for avr-stub as linked per docs.

There’s also an example setup at How to debug on Arduino mega 2560 - #2 by maxgerhardt.