nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Mon, 23 Mar 2026 10:20:30 GMT

Hello,

There is some confusion in the logs you have shared.

When we look at the logs you posted earlier, the behavior is not the same. There was a failed serial port open call, but the logs you have shared now do not fail at the serial port open call and instead fail later. So, are we looking at two different issues now?

Also, it seems that you had some log callbacks enabled that printed log messages. Are those enabled here as well?

Kind Regards,

Abhijith

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Tue, 17 Mar 2026 13:57:59 GMT

Start update
'testhost.net48.x86.exe' (CLR v4.0.30319: TestSourceHost: Enumerating source (C:\SvnWorks\Toolbox\02 Wilo.Tooling\trunkSvn\AccessoriesCatalog\BasicSmartSensor_UnitTest\bin\Debug\BasicSmartSensor_UnitTest.dll)): Loaded 'C:\Program Files\Microsoft Visual Studio\2022\Professional\Common7\IDE\Remote Debugger\x86\Runtime\Microsoft.VisualStudio.Debugger.Runtime.Desktop.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Progress: 1% UserState: Modem Update: Modem is in update mode...
The thread 14276 has exited with code 0 (0x0).
The thread 38424 has exited with code 0 (0x0).
'testhost.net48.x86.exe' (CLR v4.0.30319: TestSourceHost: Enumerating source (C:\SvnWorks\Toolbox\02 Wilo.Tooling\trunkSvn\AccessoriesCatalog\BasicSmartSensor_UnitTest\bin\Debug\BasicSmartSensor_UnitTest.dll)): Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\Newtonsoft.Json\v4.0_13.0.0.0__30ad4fe6b2a6aeed\Newtonsoft.Json.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Progress: 2% UserState: Modem Update: Is connected To modem...
The thread 1316 has exited with code 0 (0x0).
[UpdateModemDfu] NRFDFU_program_package return -220
The program '[29312] testhost.net48.x86.exe' has exited with code 4294967295 (0xffffffff).

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Tue, 17 Mar 2026 11:30:40 GMT

Hi Abhijith,

I'm calling the method NRFDFU_connect_to_modemdfu_target() and for both, 32bit and 64bit , the result value is "0", so it seems to me, that the connection on COM18 is established. after that I'm calling NRFDFU_program_package(). In case of 64 bit everything is OK, in case of 32bit the method NRFDFU_program_package() return -220.

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Fri, 13 Mar 2026 13:19:00 GMT

Hello Peter,

Since the standalone x64 console application can open COM18, the port itself appears to be working. However, this does not completely rule out an issue related to the 32-bit DLL, such as the port already being in use or how the process accesses the port.

To help rule this out, I recommend trying the 32-bit version of PuTTY, as mentioned in my previous response.

Kind regards,
Abhijith

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Fri, 13 Mar 2026 12:21:04 GMT

Hi Abhijith, when I just compile the standalone console app as x64, using COM18 is OK. So I doubt, that serial port is blocked by another application.

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Fri, 13 Mar 2026 10:18:15 GMT

Hello,

From the log messages you have shared:
It looks like the error occurs when Windows tries to open the serial port (COM18), and the message is coming from Windows rather than dll. This typically happens if the serial port is already in use by another program (for example another instance of the application still running).

To verify this, could you try connecting to COM18 using a 32-bit version of PuTTY? If PuTTY can open the connection, it would indicate that DLL and worker executable are running correctly and that the issue is likely related to another application holding the port. If PuTTY cannot open it, then the port may currently be locked or there may be a Windows configuration issue.

Kind Regards,

Abhijith

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Thu, 12 Mar 2026 13:08:41 GMT

Hi Abhijith,

today I created another standolone small console application with a minimized pcb modem update functionality. in the applications binary folder I copied nrfdfu.dll from your suggestion above, and also a nrfdfu_x64.dll. I got the same results, nrfdfu_x64.dll is running fine, if I compiled the console application in x64 mode. If I compile the console application in x86 mode (32 bit) your nrfdfu.dll is not executed successful, I got the below listed log messages in the console:

Progress: 0%
Progress: 0%
Progress: 0%
Progress: 0%
Progress: 0%
[*** LOG ERROR #0001 ***] [2026-03-12 13:20:10] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
Progress: 0%
Progress: 0%
Progress: 0%
Progress: 0%
[*** LOG ERROR #0011 ***] [2026-03-12 13:20:24] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0034 ***] [2026-03-12 13:20:26] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0038 ***] [2026-03-12 13:20:28] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0042 ***] [2026-03-12 13:20:30] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0046 ***] [2026-03-12 13:20:32] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0050 ***] [2026-03-12 13:20:34] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0054 ***] [2026-03-12 13:20:36] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0058 ***] [2026-03-12 13:20:39] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0062 ***] [2026-03-12 13:20:41] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0066 ***] [2026-03-12 13:20:43] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0070 ***] [2026-03-12 13:20:45] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0074 ***] [2026-03-12 13:20:47] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0078 ***] [2026-03-12 13:20:49] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0082 ***] [2026-03-12 13:20:51] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
Progress: 0%
[*** LOG ERROR #0086 ***] [2026-03-12 13:20:53] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}
Progress: 0%
[*** LOG ERROR #0090 ***] [2026-03-12 13:20:54] [ModemUARTDFU-COM18] {device or resource busy: device or resource busy}

Thanks in advance and best regards

Johannes

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Wed, 11 Mar 2026 13:25:18 GMT

Hello,

I checked with the internal team regarding this issue, and we tried to reproduce it on our side, but it seems to be working for us. I am including the steps we followed to reproduce the issue and also attaching the generated logs

The last available 32-bit version of the nRF Command Line Tools (v10.19.0 for “Windows x86 32”) was downloaded from here.

From this package, the 32-bit DLLs, the 32-bit worker executable (jlinkarm_nrf_worker.exe), and the corresponding header files were copied into a separate test directory.

A small C test application was then created to load nrfdfu.dll and call the MCUboot functions provided by the library. The application was compiled as a 32-bit executable using Visual Studio (MSVC 2019).

The target hardware used for testing was an nRF9160 running the fmfu_smp_svr sample from the nRF Connect SDK. For this setup, the test directory contained only the 32-bit versions of the DLLs and the worker executable, ensuring that no 32-bit and 64-bit components were mixed during the test.

Using this setup, the behavior where the application hangs could not be reproduced. The test application was able to proceed, and log messages indicated that firmware chunks at increasing offsets were uploaded successfully. The test was not run to completion, but the upload appeared to progress beyond the point where the failure reportedly occurs.

As an additional diagnostic step, it may be useful to enable a log callback in the DFU API. If no log messages are returned at all, it could indicate that something fails when the DLL attempts to start the worker executable.The worker (jlinkarm_nrf_worker.exe) should normally be located in the same directory as the DLL, and it is expected that the 32-bit version is used when running a 32-bit application

devzone.nordicsemi.com/.../nrf91_5F00_dfu_5F00_log.txt

Kind Regards,

Abhijith

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Wed, 11 Mar 2026 08:39:34 GMT

Hallo Abhijith,

I am NOT using Jlink in SW update, I am just connected via USB-C cable. We have created a wrapper that calls methods from your nrfdfu.dll. I case of 32 bit DLL usage I get the error below in line 286 (error code = -220 from method "NRFDFU_program_package". When operating in 64 bit mode line 282 is executed and work OK.

// Start programming
int returnCode = -1;
if ( NordicNrfDfuWrapper.IsRunningInA64BitProcess () )
{
returnCode = NRFDFU_program_package_x64 ( this.connectionHandle, filePath );
}
else
{
returnCode = NRFDFU_program_package ( this.connectionHandle, filePath );
}

Best regards

Johannes

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Mon, 09 Mar 2026 10:22:43 GMT

Hello Peter,

Sorry for the delay occurring here.
When running the 32-bit version of the application, can you confirm which SEGGER J-Link DLL is loaded? A 32-bit process must load JLinkARM.dll (32-bit), while a 64-bit process uses JLink_x64.dll

The DFU API launches a worker executable (jlinkarm_nrf_worker_*.exe) to handle the J-Link communication. When the application runs as a 32-bit process, the 32-bit version of this worker executable would typically need to be available, possibly either in the same directory as the application or somewhere in the system PATH. If only the 64-bit worker executable is present, it might be possible that the API attempts to launch that instead, which could potentially lead to the communication failing or the process hanging. Could you check whether a 32-bit jlinkarm_nrf_worker_*.exe is present and being used when running the application in 32-bit mode?

Kind Regards,

Abhijith

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Mon, 09 Mar 2026 06:55:20 GMT

Hi Aghijith,

any news on this topic?

Best regards

Johannes

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Tue, 24 Feb 2026 10:34:21 GMT

Hello Peter,

Since you marked your response as verified, I did not see the reply you posted a few days ago. It’s good that you reposted it. I have now raised this internally to check if there is any issue with the 32-bit version. I will let you know once I receive an update and share it here.

Kind Regards,

Abhijith

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Mon, 23 Feb 2026 07:43:51 GMT

Hi Abhijith,

we are currently not referening or embedding the header file nrfdfu.h. Nonetheless the 32bit package is copied in the same folder structure like when we use the 64bit package.

we have 2 folders: Nordic64Bit and Nordic32Bit containing you native dlls and header files:

Nordic64Bit

nrfdfu.dll

nrfdfu.h

nrfjprog.dll

...

Nordic32Bit

nrfdfu.dll

nrfdfu.h

nrfjprog.dll

...

these folder also include our managed C# components/wrapper files in which your native DLL is improted via DLL import like mentioned above.

When I use the 64 bit version, everthing is OK, but when I switch to 32 bit version the modem update hangs up.

Best regards and thanks in advance

Johannes

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Mon, 16 Feb 2026 09:34:19 GMT

Hi Abhijith,

we are currently not referening or embedding the header file nrfdfu.h. Nonetheless the 32bit package is copied in the same folder structure like when we use the 64bit package.

we have 2 folders: Nordic64Bit and Nordic32Bit containing you native dlls and header files:

Nordic64Bit

nrfdfu.dll

nrfdfu.h

nrfjprog.dll

...

Nordic32Bit

nrfdfu.dll

nrfdfu.h

nrfjprog.dll

...

these folder also include our managed C# components/wrapper files in which your native DLL is improted via DLL import like mentioned above.

When I use the 64 bit version, everthing is OK, but when I switch to 32 bit version the modem update hangs up.

Best regards and thanks in advance

Johannes

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Peter — Thu, 12 Feb 2026 16:36:51 GMT

Hello Abhijith,

thank you for the response. We will check and come back to you.

Best regards,

Peter

RE: nRF Command Line Tools: nrfdfu.dll 32bit version problem when updating nRF9160 firmware

Menon — Thu, 12 Feb 2026 12:14:25 GMT

Hello,

I am not aware of any known issues related to a 32-bit process. Could you please check whether nrfdfu.h is present in your installation (it is typically located under the include\ folder in the nRF Command Line Tools installation directory)? Please see the section Windows file structure.

Kind Regards,

Abhijith