Nrf54LM20A_DK vscode cannot be programmed

[john.liu]

hi:

nRF54LM20A_DK board vscode cannot be programmed.

-- west flash: using runner nrfutil -- runners.nrfutil: mass erase requested

-- runners.nrfutil: reset after flashing requested

-- runners.nrfutil: Flashing file: C:\ncs\v3.1.1-john\nrf_desktop\build\merged.hex

Error: One or more batch tasks failed:

* 1051847907: Device error: Unable to recognize the device: Unknown part number 0x00000033 (Generic)

FATAL ERROR: command exited with status 1: nrfutil --json device x-execute-batch --batch-path 'C:\ncs\v3.1.1-john\nrf_desktop\build\generated_nrfutil_batch.json' --serial-number 1051847907

[SwRa]

Hi John,

nRF54LM20A is supported from NCS v3.1.1, so it should work. Could you make sure you have the right nrfutil version. Perhaps try upgrading nrfutil using the following commands:
nrfutil self-upgrade
nrfutil upgrade

Best Regards,

Swathy

[john.liu]

Hi:
Sorry for the late reply! 

C:\Users\64619>nrfutil --version
nrfutil 8.2.0 (c910332 2026-04-21)
commit-hash: c910332307392c1f6801baadd3cc0265965803a5
commit-date: 2026-04-21
host: x86_64-pc-windows-msvc
build-timestamp: 2026-04-21T14:15:35.519234808Z
classification: nrf-external

C:\Users\64619>nrfutil self-upgrade
nrfutil is already the newest version (8.2.0)

C:\Users\64619>nrfutil upgrade
Downloading nrfutil-device-x86_64-pc-windows-msvc-2.19.4
Verifying nrfutil-device-x86_64-pc-windows-msvc-2.19.4
Updating nrfutil-device to 2.19.4
nrfutil-mcu-manager is already the newest version (0.10.2)
Downloading nrfutil-sdk-manager-x86_64-pc-windows-msvc-1.15.0
Verifying nrfutil-sdk-manager-x86_64-pc-windows-msvc-1.15.0
Updating nrfutil-sdk-manager to 1.15.0
[00:17:16] ###### 100% [Upgrade packages] Upgrade packages

After updating nrfutil, I still have the same problem.

-- west flash: using runner nrfutil
-- runners.nrfutil: mass erase requested
-- runners.nrfutil: reset after flashing requested
-- runners.nrfutil: Flashing file: C:\ncs\nrf_nrf54lm20a_usbhs_8khz_1458f16\samples\esb\esb_ptx\build_1\merged.hex
Error: One or more batch tasks failed:
* 1051847907: Device error: Unable to recognize the device: Unknown part number 0x00000033 (Generic)

FATAL ERROR: command exited with status 1: nrfutil --json device x-execute-batch --batch-path 'C:\ncs\nrf_nrf54lm20a_usbhs_8khz_1458f16\samples\esb\esb_ptx\build_1\generated_nrfutil_batch.json' --serial-number 1051847907

[SwRa]

Hi John,

The part number 0x00000033 is not a recognized nRF54LM20A identifier. For reference, the nRF54LM20A part code in FICR is 0x054BC20A and nRF54LM20B is 0x054BC20B. Refer: https://docs.nordicsemi.com/r/bundle/ps_nrf54lm20a/page/ficr.html-register.info.part. Reading 0x00000033 suggests the device may not be responding correctly over SWD/J-Link, rather than a software version issue. Could you maybe try recovering the device first as it maybe locked or in an unresponsive state.?

nrfutil device recover --serial-number 1051847907

Also, do check your J-Link version.  nrfutil-device v2.19.4 requires SEGGER J-Link v9.24a. An incompatible J-Link version can cause device recognition failures. Please also verify that the DK is connected via the IMCU USB port (not a target USB port).

Best Regards,

Swathy

[psychogenic]

This was super annoying, same for me with two LM20B boards.  Did a bunch of things, had all the latest version of SDK, nrfutil, etc then even downgraded JLink to version 9.24a, no go.  But solution: upgrading nrfutil devices.

Running an `nrfutil upgrade` did this:

nrfutil-completion is already the newest version (1.5.0)
Downloading nrfutil-device-x86_64-unknown-linux-gnu-2.19.4
Verifying nrfutil-device-x86_64-unknown-linux-gnu-2.19.4
Updating nrfutil-device to 2.19.4
[00:00:05] ###### 100% [Upgrade packages] Upgrade packages

And things started working, even if I'd done the same only 2 days prior..?  In any case, re-updated JLink to v9.6.0 and it still works.

[john.liu]

Hi SwRa:

Thank you for your help!

"nRF Connect for Desktop" can be programmed, but "VScode" cannot.

After using "nrfutil device recover --serial-number 1051847907", it is also cannot.