Could not connect to target when use GDB debug in VSCode

[lkb]

Hi,

nRF54L15 DK + VSCODE + nRF connect for VSCODE,

I test example peripheral_uart, when click debug to start debugging with GDB，it show error：

Starting: "C:\Program Files\SEGGER\JLink_V794a\JLinkGDBServerCL.exe" -if SWD -speed 4000 -device nRF54L15_M33 -select usb=1057795718 -port 9808 -rtos GDBServer/RTOSPlugin_Zephyr -singlerun -nogui -halt -noir -silent

Starting: "C:\ncs\toolchains\b8b84efebd\opt\zephyr-sdk\arm-zephyr-eabi\bin\arm-zephyr-eabi-gdb.exe" --interpreter=mi -q

Could not connect to target.

Please check power, connection and settings.

"C:\Program Files\SEGGER\JLink_V794a\JLinkGDBServerCL.exe" exited with code -3 (0xFFFFFFFD).

But if I change nRF54L15_M33 to Cortex-M33, and delete option "-silent" , and run the command in windows terminal, it looks ok:

Connecting to J-Link...
J-Link is connected.
Firmware: J-Link OB-nRF5340-NordicSemi compiled Jul 8 2025 10:15:34
Hardware: V1.00
S/N: 1057795718
Feature(s): RDI, FlashBP, FlashDL, JFlash, GDB
Checking target voltage...
Target voltage: 3.30 V
Listening on TCP/IP port 13985
Connecting to target...
Core security extensions: Implemented
Connected to target
Waiting for GDB connection...

So, how to fix this error ?

Thanks.

[lkb]

But earlier, I modified parameters in zephyr\scripts\west_commands\runners\jlink.py. Why didn't it take effect? Why did the parameters remain the same when starting GDB?

[Priyanka]

Hi,

Glad to hear that you got it working. Official J-Link support for nRF54L15 was added only recently, so older packs (like v794a) might not recognize the device name.

Also, VS Code’s nRF Connect debugger doesn’t use Zephyr’s runner scripts, so edits there won’t affect the extension’s debug session.

-Priyanka