Error when fetching device versions: readFwInfo error

Hi I've just started developing with the nrf52840 and Ive been following the official documentation on how to use the programmer shipped with nRF Connect.

Unfortunately when I select the device in the respective menu I get the following error and I'm not able to do anythin on the soc.

Error when fetching device versions: readFwInfo error

I'm currently using Linux with nrf connect 3.80 and jlink 6.88a (I've tried with nRF Connect 3.9 but I had the exact same issue).

Has anyone managed to solve this problem?

  • You're using the nRFConnect Programmer application, right? What version of the Programmer are you seeing this issue on (it should work with v2.0.0)?

    An issue with nRFConnect v3.80 is that when a J-Link device is connected to your computer without the device being connected to a DK or SoC due to some enumeration issues with J-Link devices. There are two possible workarounds if you encounter this issue.

    The first is to downgrade to 3.7 and install app versions compatible with 3.7:

    1. Download the latest 3.7 version of nRF Connect for Desktop from (for macOS this is 3.7.2, for Windows and Linux 3.7.1).
    2. After starting nRF Connect for Desktop 3.7 a prompt will come up about the 3.8 upgrade. Click “No” on this.
    3. In the Settings, click on “Add source”, enter the URL and click “Add”.
    4. Back in the list of all apps, all apps should show up twice now, one with “official” below them and one with “3.7 compatible apps” below them. If you want to hide the incompatible versions, click on “Filter” and deselect “Official”.
    5. Install the apps you need in the old versions and use them.

    The other is to make sure all J-Link devices are disconnected before launching nRFConnect. Then launch an nRFConnect app and connect the device you want to use and select it in the nRFConnect app before connecting any other devices.

    Best regards,


  • Is this supposed to be fixed by now? Asking because i am experience the same issue with nRF Connect for Desktop v3.11.0.

Reply Children
  • Hi,

    Yes, this is supposed to be fixed as of v3.9.1 I believe. Do you have the same exact issue as described in this case? With an "Error when fetching device versions: readFwInfo error" in v3.11.0 of the nRF Connect for Desktop and v3.0.0 of the Programmer app? What J-Link version are you running, and what board are you trying to program?

    Best regards,


  • Yes. I am using a (never used before) nrf52840 dongle. Took it straight from the static shield bag. It's red LED is pulsing.

    This is the output I am getting when connecting to the device:

    18:42:04.678	Using nrf-device-lib-js version: 0.4.5
    18:42:04.678	Using nrf-device-lib version: 0.11.0
    18:42:04.679	Using nrfjprog DLL version: 10.15.1
    18:42:04.679	Using JLink version: JLink_V7.64c
    18:42:04.718	Installed JLink version does not match the provided version (V7.58b)
    18:42:07.733	Using @nordicsemiconductor/nrf-device-lib-js to communicate with target via USB SDFU protocol
    18:42:07.736	Error when fetching device versions: readFwInfo error