Can't connect via RTT on nRF9151 custom board

[Guillaume59]

Hello,

I have a problem with a custom board using a nRF9151.

I can flash the nRF9151 and it seams to flash successfully (I tried with a blinky program and the leds start blinking).

But a soon as I try to use RTT via nrfconnect for VScode to get logs, the board stops working and i am not getting any logs.

I think it is a problem with my configuration and maybe my nrfutil installation because when i use J-link RTT viewer (v8.18) to connect to the board, i get the same problem with the following logs :

LOG: J-Link RTT Viewer V8.18: Logging started.
LOG: Terminal 0 added.
LOG: Connecting to J-Link via USB...
LOG: Device "NRF9151_XXCA" selected.
LOG: ConfigTargetSettings() start
LOG: ---Setting ROM table---
LOG: ConfigTargetSettings() end - Took 37us
LOG: InitTarget() start
LOG: CTRL-AP indicates that the device is secured.
For debugger connection the device needs to be unsecured.
Note: Unsecuring will trigger a mass erase of the internal flash and UICR registers.


LOG: Executing default behavior previously saved in the registry.
LOG: Device will be unsecured now.
LOG: InitTarget() end - Took 287ms
LOG: Found SW-DP with ID 0x6BA02477
LOG: DPIDR: 0x6BA02477
LOG: CoreSight SoC-400 or earlier
LOG: AP map detection skipped. Manually configured AP map found.
LOG: AP[0]: AHB-AP (IDR: Not set, ADDR: 0x00000000)
LOG: AP[0]: Core found
LOG: AP[0]: AHB-AP ROM base: 0xE00FF000
LOG: CPUID register: 0x410FD212. Implementer code: 0x41 (ARM)
LOG: Feature set: Mainline
LOG: Cache: No cache
LOG: Found Cortex-M33 r0p2, Little endian.
LOG: FPUnit: 8 code (BP) slots and 0 literal slots
LOG: Security extension: implemented
LOG: Secure debug: enabled
LOG: CoreSight components:
LOG: ROMTbl[0] @ E00FF000
LOG: [0][0]: E000E000 CID B105900D PID 000BBD21 DEVARCH 47702A04 DEVTYPE 00 Cortex-M33
LOG: [0][1]: E0001000 CID B105900D PID 000BBD21 DEVARCH 47701A02 DEVTYPE 00 DWT
LOG: [0][2]: E0002000 CID B105900D PID 000BBD21 DEVARCH 47701A03 DEVTYPE 00 FPB
LOG: [0][3]: E0000000 CID B105900D PID 000BBD21 DEVARCH 47701A01 DEVTYPE 43 ITM
LOG: [0][5]: E0041000 CID B105900D PID 002BBD21 DEVARCH 47724A13 DEVTYPE 13 ETM
LOG: [0][6]: E0042000 CID B105900D PID 000BBD21 DEVARCH 47701A14 DEVTYPE 14 CSS600-CTI
LOG: RTT Viewer connected.

I also can't recognize the SIP from nrf connect for vscode and i get the following output when trying "Refresh the Connected Devices" :

[17:20:12] nrfutil-device device-info --serial-number 001050902774 --skip-overhead --json
[17:20:12] Error: One or more device info tasks failed:
 * 1050902774: Unable to find worker executable: Custom { kind: NotFound, error: "Failed to find file plugin-probe-worker. Looked for file in <none>, <none>, C:\\Users\\VssAdministrator\\.cargo\\registry\\src\\eu.files.nordicsemi.com-aeee3781a8ecf169\\target/release\\plugin-probe-worker.exe and c:\\Users\\Guillaume\\.vscode\\extensions\\nordic-semiconductor.nrf-connect-2025.9.754-win32-x64\\platform\\nrfutil\\bin\\plugin-probe-worker.exe" } (Generic)

It seems every command involving nrfutil fails (i also can't recognize a nrf52840 on the same custom board, but flashing and logs with RTT are successfull).

I am using nrf connect for desktop V3.0.0 and nrfutil is udate to the latest version (8.1.1).

Any help wold be welcomed,

Regards.

Guillaume;

[pr0b3]

Hi , I've face similar issue ,I Solved it , but my simptoms were little bit different : 

I will document it here in case somebody will face the same problem , before Nordic will address it.

• Installed SDK and Toolchains 3.1.0
• I have OB J-link .
• J-Link 8.6v Installed.
• Working with nrfutil

J-link was recognized by nrf Connect Extension , but on "Connected Devices" I've had situation  :

i.e. SoC NRF52833 ,did not recognized. Althought, I was able to flash and debug the SoC  via "Actions Menu"

more over, when I've tried to apply one of hardware commands (reset , erase , recover) to  the board via "Connected Devices" Menu , I've received the error message that It failed with message : 

[11:22:51] nrfutil-device device-info --serial-number 000052007917 --skip-overhead --json
[11:22:51] Error: One or more device info tasks failed:
 * 52007917: Unable to find worker executable: Custom { kind: NotFound, error: "Failed to find file plugin-probe-worker. Looked for file in <none>, <none>, C:\\Users\\VssAdministrator\\.cargo\\registry\\src\\eu.files.nordicsemi.com-aeee3781a8ecf169\\target/release\\plugin-probe-worker.exe and c:\\Users\\%USERNAME%\\.vscode\\extensions\\nordic-semiconductor.nrf-connect-2025.9.754-win32-x64\\platform\\nrfutil\\bin\\plugin-probe-worker.exe" } (Generic)

Also ,when I've performed the same command 

nrfutil device device-info --skip-overhead --json

manually from terminal , everything worked correctly.

From your and my message I can understand that problem is with extension's pathes and nrfutil related.

What helped to me is just copying the 

plugin-probe-worker.exe

 file from 

C:\Users\%USER%\.vscode\extensions\nordic-semiconductor.nrf-connect-2025.9.754-win32-x64\platform\nrfutil\lib\nrfutil-device

to 

C:\Users\%USER%\.vscode\extensions\nordic-semiconductor.nrf-connect-2025.9.754-win32-x64\platform\nrfutil\bin

[frankenboom]

I had this exact same issue on M1 MAC (I think it started randomly, but possibly after updating an nrf extension not sure) and this fixed it. Thank you.

[vincent_itk]

Go the same error on Linux Ubuntu 25.04. Here is how to fix it :

ln -s ~/.vscode/extensions/nordic-semiconductor.nrf-connect-2025.9.754-linux-x64/platform/nrfutil/lib/nrfutil-device/plugin-probe-worker ~/.vscode/extensions/nordic-semiconductor.nrf-connect-2025.9.754-linux-x64/platform/nrfutil/bin/plugin-probe-worker 

Seems to have an error in the nrf vscode extension

[Guillaume59]

Hello, 

Yes I had exactly this problem, I also had all the other symptoms that you described. Your solution did fix the SIP detection problem in VScode, thank you very much.

Although I also have APPROTECT enabled as mentioned by Michal, but it is not really blocking as it prevents debugging but not log reading.