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  VS Arduino › Visual Micro › Hardware Debugging (GDB, GDB WiFi, GDB Stub) › ESP32 hardware debug not starting
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Normal Topic ESP32 hardware debug not starting (Read 71 times)
Jeremy_Russell
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ESP32 hardware debug not starting
Jun 11th, 2026 at 2:24pm
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I have used hardware debugging in the past with good success.  I have recently been trialing the new version with VS2026, but cannot get the debugger to connect either by compile and debug or by attach to process.

I normally use a F2232 Single board, but have also tried an ESP-PROG board.  Changed drivers with Zadig, etc., double check connections, but no success.

I am using a test blink application.  Attached are the error messages and the build output.

I have spent hours on this - help!

  
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Simon@Visual Micro
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Re: ESP32 hardware debug not starting
Reply #1 - Jun 11th, 2026 at 2:29pm
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Thanks for the report, can you attach or email the "TestDebug.ino_DebugOpenOCD.log" from the build folder?

Also please confirm you have done a find and replace on the attached logs for the username (some paths look a bit mangled with \_\ in).
  
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Re: ESP32 hardware debug not starting
Reply #2 - Jun 11th, 2026 at 3:36pm
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Thanks for the OpenOCD Log, it looks to be failing to connect to OpenOCD (the layer below GDB).

I have the same setup on my machine here working (VS2026, ESP32 Dev Board, v3.3.8 Core, ESP-PROG) however wiring/interference can make a difference.

Can you add a local board.txt to the project (vMicro > Add Code > Add Local Board.txt) and paste in the attached entry.  Then rebuild and upload the project and try debugging again.

NOTE: You have the Automatic FS Upload enabled with no Data folder so this can also be turned off.
  
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Jeremy_Russell
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Re: ESP32 hardware debug not starting
Reply #3 - Jun 11th, 2026 at 10:34pm
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Switched off the FS upload - used for my main application.

I added the board.txt as advised.  Still doesn't start the debugger - I get the following error message:

Unable to start debugging. Unexpected GDB output from command "-target-select remote localhost:3333". Remote communication error.  Target disconnected: error while reading: Invalid argument.

followed by another popup saying "The debugger did not start correctly, child debug processes killed"
  
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Simon@Visual Micro
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Re: ESP32 hardware debug not starting
Reply #4 - yesterday at 1:11pm
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Thanks for the update, please try the attached settings in the local board.txt which remove the resets from the initialisation process as well.

Can you also confirm the blink sketch is not using any of the JTAG pins (12-15)?

If it still fails, try manually resetting the board before attaching the debugger as this can sometimes help.

If it still fail can you attach the OpenOCD log and the first error message again?
  
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Jeremy_Russell
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Re: ESP32 hardware debug not starting
Reply #5 - yesterday at 5:43pm
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Hi, thanks for the reply.  I can confirm that IOs 12-15 are not used for other things.  The bare board blink program uses IO 2.

I tried the new board.txt, still no success.  I also tried with my original F2232H Single, attached to my application board, but with blink program.  Error message as follows:

ESP32 PROG:
===========
After Hit start to build and debug, target board is frozen:
Unable to start debugging. Unexpected GDB output from command "-target-select remote localhost:3333". Remote communication error.  Target disconnected: error while reading: Invalid argument.

After reset target, blink again, Debug->Attach to process:
Unable to start debugging. Unexpected GDB output from command "-target-select remote localhost:3333". Remote replied unexpectedly to 'vMustReplyEmpty': vCont;c;C;s;S

F2232H Single
=============
Compile and debug:
Unable to start debugging. Unexpected GDB output from command "-target-select remote localhost:3333". Remote replied unexpectedly to 'vMustReplyEmpty': vCont;c;C;s;S

After reset, blink, attach:
Unable to start debugging. Unexpected GDB output from command "-target-select remote localhost:3333". Remote replied unexpectedly to 'vMustReplyEmpty': vCont;c;C;s;S

The manual reset was necessary for the attach debugs, as the blink app was normally frozen after the build-debug attempt.

At this point, the debugger driver seems to have got stuck as a single USB->Serial.

Switched to laptop, duplicated problem, attached OCD log file.

I notice I have the same problem as on desktop of simultaneous connection of ESP32-DEV module, and ESP32-PROG debugger results in automatic firmware upload failing.

Log is from Debug-Attach


« Last Edit: yesterday at 6:04pm by Jeremy_Russell »  
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Jeremy_Russell
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Re: ESP32 hardware debug not starting
Reply #6 - yesterday at 11:48pm
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I'm on US time, so still working at this.

I found connecting both the debugger and the USB of the ESP32-WROOM caused some lockups.  I was suspecting a ground loop.  Google suggests that may be a problem.

I changed connections to power the ESP-32WROOM from the ESP32-PROG (setting jumper to 5V, and connecting to VIN.  The blink application runs.  However, I cannot do a debug attach to process - it gives error:

Unable to start debugging. Unexpected GDB output from command "-target-select remote localhost:3333". could not connect (error 138): The system tried to join a drive to a directory on a joined drive.

Content of *OpenOCD.log:
adapter speed: 500 kHz
none
Info : auto-selecting first available session transport "jtag". To override use 'transport select <transport>'.
Info : Configured 2 cores
esp32 interrupt mask on
Info : clock speed 500 kHz
-----------------------------

I also cannot upload via the ESP32-PROG


  
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