nrfutil device program results in [sdfu] firmware file extension .hex is not supported

[TCdeveloper]

I am trying to use my nRF52840 as a sniffer and am attempting to follow the directions at:

Programming the nRF Sniffer firmware (nordicsemi.com)

Note that I have downloaded sniffer firmware available at:

nRF Sniffer for Bluetooth LE - Downloads - nordicsemi.com

When I attempt to use command line tool nrfutil, I get the following response:

D:\Nordic>nrfutil device program --serial-number D9561E4XXXX --firmware sniffer_nrf52840dongle_nrf52840_4.1.1.hex
[00:00:00] ------ 0% [D9561E4DXXXX] Failed, [sdfu] firmware file extension .hex is not supported
Error: One or more program tasks failed:
* D9561E4DXXXX: [sdfu] firmware file extension .hex is not supported, code: Argument

I am not sure what I am doing wrong here. The instructions specifically say:

nrfutil device program --serial-number <serial-number> --firmware <hex>

Help! And thank you in advance.

[nordicator_prim3]

Hi,

Which actual hardware are you using, nrf52840dk or the dongle?

Have you tried the .zip just to see if it would take that?

[TCdeveloper]

The nRF52840 dongle.

The files that came with the download did not include a .zip file. This is what I have.