I bought a used Lytro Illum with firmware 1.0.1 (15).
These instructions said to just put the last firmware version file ILLUM-update-2.0.0 (42)-u.lfu on the SD card and turn on the camera with that SD card.
However this worked best for me:
Reformat the SD card from the camera.
Take one picture.
Turn off the camera.
Remove the SD card and place it in a PC.
-
Place the .lfu firmware file in:
The root of the SD card.
The DCIM directory.
The DCIM\100PHOTO directory.
The LOST.DIR directory.
The MISC directory.
Unmount/eject the SD card.
Put the SD card into the Illum.
Start the Illum.
It should now find a firmware update and suggest to update the firmware.
Update the firmware.
With these steps I updated:
1.0.1 (15) to 1.0.2 (19)
1.0.2 (19) to 1.1.0 (31)
1.1.0 (31) to 2.0.0 (42)
I probably should have been able to go from 1.0.1 (15) to 2.0.0 (42) with above steps, but by the time I had these steps figured out this was the upgrade route I had taken.