Issue flashing and debugging with STLINK-V3SET + ISO in VSCode

[DEs]

Hi there!

I’m having an issue when flashing / debugging with the STLINK-V3SET + ISO (V3J17M11B6S1). From VSCode I get the error Error: Unable to connect to the target device, Access port is not valid. This issue does not appear when using STLINK-V3MINI (V3J17M10).

I updated STM32CubeProgrammer vscode bundle to 2.23.0 and then code upload / debug worked once and now I’m getting the Access port is not valid error again. I tried setting the “serverApID” in the launch.json to force the correct Access port however I can’t get this to work.

Is this a known issue? 

I made a log for both debuggers:

STLINK-V3MINI	V3J17M10:

STMicroelectronics ST-LINK GDB server. Version 7.13.0
Copyright (c) 2026, STMicroelectronics. All rights reserved.

Starting server with the following options:
        Persistent Mode            : Disabled
        Logging Level              : 1
        Listen Port Number         : 61234
        Status Refresh Delay       : 15s
        Verbose Mode               : Disabled
        SWD Debug                  : Enabled
        InitWhile                  : Enabled

Waiting for debugger connection...
GNU gdb (GNU Tools for STM32 14.3.rel1.20251027-0700) 15.2.90.20241229-git
Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-w64-mingw32 --target=arm-none-eabi".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
add-symbol-file "D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf"
add symbol table from file "D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf"
(y or n) [answered Y; input not from terminal]
Reading symbols from D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf...
Debugger connected
Waiting for debugger connection...
Reset_Handler () at D:/DEV/application/CubeMX/NUCLEO_C562RE/user_modifiable/Device/STM32C562RET6/startup_stm32c562xx.c:258
258	{
connected to remote target localhost:61234
tbreak main
Temporary breakpoint 1 at 0x8004298: file D:/DEV/application/application/src/main_app.c, line 122.
Note: automatically using hardware breakpoints for read-only addresses.
load "D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf"
Loading section .vectors, size 0x188 lma 0x8000000
Loading section .text, size 0x21068 lma 0x8000190
Loading section .rodata, size 0x8048 lma 0x80211f8
Loading section .ARM, size 0x8 lma 0x8029240
Loading section .init_array, size 0x8 lma 0x8029248
Loading section .fini_array, size 0x8 lma 0x8029250
Loading section .copy.table, size 0xc lma 0x8029258
Loading section .zero.table, size 0xc lma 0x8029264
Loading section .data, size 0x3288 lma 0x8029270
      -------------------------------------------------------------------
                       STM32CubeProgrammer v2.22.0
      -------------------------------------------------------------------

Log output file:   C:\Users\DEs\AppData\Local\Temp\STM32CubeProgrammer_a32308.log
ST-LINK SN  : 002F00453137510D33333639
ST-LINK FW  : V3J17M10
Board       : STLINK-V3MINI
Voltage     : 3.28V
SWD freq    : 8000 KHz
Connect mode: Under Reset
Reset mode  : Hardware reset
Device ID   : 0x44E
Revision ID : Rev Y
Device name : STM32C5x
NVM size  : 512 KBytes
Device type : MCU
Device CPU  : Cortex-M33
BL Version  : 0x101
Debug in Low Power mode enabled

Opening and parsing file: ST-LINK_GDB_server_a32308.srec

Memory Programming ...
  File          : ST-LINK_GDB_server_a32308.srec
  Size          : 177.24 KB
  Address       : 0x08000000

Erasing memory corresponding to segment 0:
Erasing internal memory sectors [0 22]
Download in Progress:

File download complete
Time elapsed during download operation: 00:00:00.575
Start address 0x0800ccc0, load size 181488
Transfer rate: 184 KB/sec, 9552 bytes/write.
set *(int *)0xE000ED14=*(int *)0xE000ED14|0x10
set *(int *)0xE000EDFC=*(int *)0xE000EDFC|0xff0
set *(unsigned int *)0xe00e4004|=0x7
set *(unsigned int *)0xe00e4008|=0x1800

In the Debug Console view you can interact directly with GDB.
To display the value of an expression, type that expression which can reference
variables that are in scope. For example type '2 + 3' or the name of a variable.
Arbitrary commands can be sent to GDB by prefixing the input with a '>',
for example type '>show version' or '>help'.


Temporary breakpoint 1, main () at D:/DEV/application/application/src/main_app.c:122
122	  System_Init();


STLINK-V3SET 	V3J17M11B6S1

STMicroelectronics ST-LINK GDB server. Version 7.13.0
Copyright (c) 2026, STMicroelectronics. All rights reserved.

Starting server with the following options:
        Persistent Mode            : Disabled
        Logging Level              : 1
        Listen Port Number         : 61234
        Status Refresh Delay       : 15s
        Verbose Mode               : Disabled
        SWD Debug                  : Enabled
        InitWhile                  : Enabled

Waiting for debugger connection...
GNU gdb (GNU Tools for STM32 14.3.rel1.20251027-0700) 15.2.90.20241229-git
Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-w64-mingw32 --target=arm-none-eabi".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
add-symbol-file "D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf"
add symbol table from file "D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf"
(y or n) [answered Y; input not from terminal]
Reading symbols from D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf...
Debugger connected
Waiting for debugger connection...
Reset_Handler () at D:/DEV/application/CubeMX/NUCLEO_C562RE/user_modifiable/Device/STM32C562RET6/startup_stm32c562xx.c:258
258	{
connected to remote target localhost:61234
tbreak main
Temporary breakpoint 1 at 0x8004298: file D:/DEV/application/application/src/main_app.c, line 122.
Note: automatically using hardware breakpoints for read-only addresses.
load "D:/DEV/application/build/debug_GCC_NUCLEO-C562RE/NUCLEO_C562RE.elf"
Loading section .vectors, size 0x188 lma 0x8000000
Loading section .text, size 0x21068 lma 0x8000190
Loading section .rodata, size 0x8048 lma 0x80211f8
Loading section .ARM, size 0x8 lma 0x8029240
Loading section .init_array, size 0x8 lma 0x8029248
Loading section .fini_array, size 0x8 lma 0x8029250
Loading section .copy.table, size 0xc lma 0x8029258
Loading section .zero.table, size 0xc lma 0x8029264
Loading section .data, size 0x3288 lma 0x8029270
      -------------------------------------------------------------------
                       STM32CubeProgrammer v2.22.0
      -------------------------------------------------------------------

Log output file:   C:\Users\DEs\AppData\Local\Temp\STM32CubeProgrammer_a20172.log
Error: Unable to connect to the target device, Access port is not valid.
Encountered Error when opening C:\Users\DEs\AppData\Local\stm32cube\bundles\programmer\2.22.0+st.1\bin\STM32_Programmer_CLI.exe
Error in STM32CubeProgrammer
Error finishing flash operation
cube is killed by signal SIGTERM

Kind regards,
Dennis

[Kouthair]

Hello ​@DEs & welcome to ST Community! 
I was unable to reproduce the error that you are encountering here with your same setup (STLINK-V3SET & firmware version=V3J17M11B6S1 + STM32C562RE) as it has worked well as shown in the screenshot below.

Could you check if you possibly did something different in the wiring when changing from STLINK-V3MINIE to STLINK-V3SET? Any other useful information that might help would be much appreciated.

[DEs]

Hi ​@Kouthair,

Thanks for investigation the issue. I’m not in the office today however we have the B-STLINK-ISOL module stacked on top of the STLINK-V3SET.

Wiring issues seem very unlikely we use 1 to 1 cable that came with the STLINK-V3SET.

The test I did was connect STLINK-V3MINIE to the DEBUG_IN port on the NUCLEO-C562RE then program + debug was working. The 2nd test I did was connect STLINK-V3SET + B-STLINK-ISOL tot the DEBUG_IN port of that same NUCLEO-C562RE board. Then i got that ‘Access port is not valid’ message.

My colleague did get the STLINK-V3SET + B-STLINK-ISOL program + debug working once with STM32CubeProgrammer v2.23.0 once. I believe a 2nd try resulted in the same ‘Access port is not valid’ message.

I never had issues with either board using the STM32CubeProgrammer GUI tool.

 

[DEs]

I just re-tried program and attach using STLINK-V3SET + B-STLINK-ISOL and it failed in vscode. Again the Access port is not valid message. Without touching the wiring I’m able to connect to it using STM32CubeProgrammer:
 

 

I updated firmware to V3J17M11B6S1 and get the same error message.

Again I don’t have this issue with STLINK-V3MINIE. 

This is my launch,json:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "type": "stlinkgdbtarget",
            "request": "launch",
            "name": "Program + Connect",
            "cwd": "${workspaceFolder}",
            "preBuild": "${command:st-stm32-ide-debug-launch.build}",
            "runEntry": "main",
            "serverApID": "1",
            "serverReset": "Connect under reset",
            "imagesAndSymbols": [
                {
                    "imageFileName": "${workspaceFolder}/bin/HW_R00.hex",
                    "symbolFileName": "${workspaceFolder}/bin/HW_R00.elf"
                }
            ],
            "serverSerialNumber": "005300273235511438363730"
        }
    ]
}

I did try serverApID 0 as well without success.
 

[DEs]

Ok I found the issue, I detached the B-STLINK-ISOL from the STLINK-V3SET and I was able to program / debug my target. I also noticed the SWD freq: 8000 KHz.

 

So I re-attached the isolator and tried again with option "serverInterfaceFrequency": "8000" in the launch,json.

Now I’m able to program / debug my target as I wish.

Somehow the “Auto” options seem to be broken as it does not re-try at a lower frequency.

Thanks for helping, my issue is resolved now.