Skip to main content
Associate II
February 13, 2026
Question

B-G431B-ESC1 Not Detected by STM32CubeProgrammer After Failed Connection

  • February 13, 2026
  • 3 replies
  • 293 views

I am using the B-G431B-ESC1 board, which connects to my laptop via a micro-USB to USB-A cable. After a failed connection attempt, the board is no longer detected by STM32CubeProgrammer. Additionally, a file named "File.txt" is created on the MCU after the failed attempt.

The contents of the file are:
"The interface firmware FAILED to reset/halt the target MCU."

This file appears to be causing issues with the connection to STM32CubeProgrammer.

Could anyone please help me resolve this issue?

Ankitesh_0-1770964987992.pngAnkitesh_1-1770965020484.png

 

3 replies

AnkiteshAuthor
Associate II
February 13, 2026

it is FAIL.TXT not File.txt

Senior III
February 13, 2026

You can try flashing with CubeIde.

AnkiteshAuthor
Associate II
February 13, 2026

Same issue with STM32CubeIDE.

GMA
Technical Moderator
February 13, 2026

Hello @Ankitesh,

Has the board been modified around SWD signal path?
Refer to the STM32CubeProgrammer user manual and try using Connect under reset mode.

If you agree with the answer, please accept it by clicking on 'Accept as solution'.Best regards.GMA
February 17, 2026

This usually happens when the ST-LINK can’t reset or halt the MCU after a failed flash/debug attempt — the File.txt is just a log, not the actual problem.

Try this:

  • In STM32CubeProgrammer, select “Connect Under Reset”

  • Lower the SWD frequency (e.g., 100 kHz)

  • Fully power cycle the board and try again

  • Also check for ST-LINK firmware updates

In most cases, connecting under reset with a lower SWD speed fixes it.

AnkiteshAuthor
Associate II
February 18, 2026

Answer:

  • In STM32CubeProgrammer, select “Connect Under Reset”

  • Lower the SWD frequency - tried on different frequencies i.e. 100kHz, 50kHz, 25kHz, 15kHz. 
  • Fully power cycle the board and try again - done during test

  • Also updated ST-LINK firmware updates

 

But same result occurs again.