Not able to flash nRF54

RE: Not able to flash nRF54

BloPoPs — Mon, 22 Sep 2025 15:48:10 GMT

I had the same problem after launching a project in debug mode, a timeout occured and then unable to flash/recover/reset the board throug the VS Code interface (panel "NRF CONNECT:CONNECTED DEVICES"). I fix it by installing JLink v8.60 and launching "J-Link.exe" on a new terminal (outside VS Code). A pop up appeared saying it will recover the board, clicked OK. It is now working with VS Code and debug mode.

RE: Not able to flash nRF54

Kazi Afroza Sultana — Thu, 04 Sep 2025 13:29:23 GMT

Hello,

You can try to recover the DK by nrfutil device recover command and see if the error persists.

RE: Not able to flash nRF54

summersun — Mon, 01 Sep 2025 09:40:07 GMT

Hi, same problem with v8.42 as below.

2025-09-01T09:33:12.215Z INFO Initialising the bundled nrfutil device
2025-09-01T09:33:12.216Z DEBUG Started watching devices
2025-09-01T09:33:13.202Z INFO Using the bundled core version for nrfutil device: 8.1.1
2025-09-01T09:33:13.308Z INFO Using nrfutil-device version: 2.10.2
2025-09-01T09:33:13.308Z INFO Using nrf-device-lib version: 0.17.71
2025-09-01T09:33:13.308Z INFO Using nrf-probe version: 0.38.0
2025-09-01T09:33:13.308Z INFO Using JLink version: JLink_V8.42
2025-09-01T09:33:13.309Z INFO Your version of SEGGER J-Link (8.42) is newer than the one this app was tested with (8.18). The tested version is not required, and your J-Link version will most likely work fine. If you get issues related to J-Link with your devices, use the tested version.
2025-09-01T09:33:13.322Z WARN It looks like you have installed JLink using 64-bit Apple M1 Installer, but currently we only support their Universal Installer for your system.
2025-09-01T09:33:13.322Z WARN Please install JLink: www.segger.com/.../JLink_MacOSX_V818_universal.pkg
2025-09-01T09:33:15.220Z DEBUG Selected device: nRF54L15 DK
2025-09-01T09:33:15.242Z DEBUG Changed step: Info
2025-09-01T09:33:16.612Z DEBUG Changed step: Rename
2025-09-01T09:33:17.311Z DEBUG Changed step: Program
2025-09-01T09:33:29.614Z ERROR [ProbeLib] [2025-09-01 09:33:29.614017Z] Failed to initialize worker: Timed out waiting for response from worker.
2025-09-01T09:33:33.844Z ERROR [ProbeLib] [2025-09-01 09:33:33.844268Z] Trace channel disconnected unexpectedly.
2025-09-01T09:33:33.848Z ERROR [ProbeLib] [2025-09-01 09:33:33.848076Z] Worker terminated by signal 9.
2025-09-01T09:33:33.848Z ERROR [ProbeLib] [2025-09-01 09:33:33.848122Z] Error output of terminated worker:

error with https://www.segger.com/downloads/jlink/JLink_MacOSX_V818_universal.pkg

2025-09-01T09:30:42.524Z INFO Initialising the bundled nrfutil device
2025-09-01T09:30:42.526Z DEBUG Started watching devices
2025-09-01T09:30:43.572Z INFO Using the bundled core version for nrfutil device: 8.1.1
2025-09-01T09:30:43.678Z INFO Using nrfutil-device version: 2.10.2
2025-09-01T09:30:43.679Z INFO Using nrf-device-lib version: 0.17.71
2025-09-01T09:30:43.679Z INFO Using nrf-probe version: 0.38.0
2025-09-01T09:30:43.679Z INFO Using JLink version: JLink_V8.18
2025-09-01T09:30:45.530Z DEBUG Selected device: nRF54L15 DK
2025-09-01T09:30:45.551Z DEBUG Changed step: Info
2025-09-01T09:30:49.395Z DEBUG Changed step: Rename
2025-09-01T09:30:50.478Z DEBUG Changed step: Program
2025-09-01T09:31:03.555Z ERROR [ProbeLib] [2025-09-01 09:31:03.553444Z] Failed to initialize worker: Timed out waiting for response from worker.
2025-09-01T09:31:07.773Z ERROR [ProbeLib] [2025-09-01 09:31:07.772947Z] Trace channel disconnected unexpectedly.
2025-09-01T09:31:07.776Z ERROR [ProbeLib] [2025-09-01 09:31:07.776647Z] Worker terminated by signal 9.
2025-09-01T09:31:07.777Z ERROR [ProbeLib] [2025-09-01 09:31:07.776681Z] Error output of terminated worker:

Tried with another nRF DK, ok to flash.

RE: Not able to flash nRF54

Kazi Afroza Sultana — Fri, 29 Aug 2025 12:20:00 GMT

You need to install correct version of Jlink working with NCS. you can see the j-link information here in the log as well

RE: Not able to flash nRF54

summersun — Fri, 29 Aug 2025 09:58:11 GMT

nRF54L15 development kit. it should have debugger onboard and no need external Jlink right?

RE: Not able to flash nRF54

Kazi Afroza Sultana — Fri, 29 Aug 2025 08:58:43 GMT

Hello,

Try to use the latest version of J-link.

''Use the J-Link v8.42 when working with the nRF Connect SDK, as also listed in the Install prerequisites section on the nRF Connect SDK installation page.''

For nRF54 series devices, nrfutil is required for flashing. Make sure you have the correct and up-to-date version of nrfutil installed globally, as west and other tools rely on it for nRF54 devices. You can check if you hve latest version of nrfutil by this nrfutil --version command.

By the way which version of DK you are using and which sample/application you are running on the DK?

Thanks.

Kazi