Bootloader Flashing Error - Nordic NRF52840 USB Dongle

[ashokr.com]

Hi All,

Im trying to flash the pre boot-loader from here github.com/.../releases

to my nordic usb dongle.

hex-> mdk_nrf52840_dongle_bootloader-0.3.2_s140_6.1.1.hex
Im getting the DFU error.
DFU failed: Error message for known extended error code from DFU target: The init packet does not contain a signature. This bootloader requires DFU updates to be signed.

Please help on this.
Ashok R

[ashokr.com]

Thank you! now i got NRF52 Dev Kit so no issues!