Invalid custom flash image format

i downloaded a file of n920c but when i choose fiel and start flash

show this error

Quote:

SW Change
20/12/2015
5:10:59
PM

SW Change
20/12/2015
5:10:59
PM

SW Change
20/12/2015
5:10:59
PM

[Firmware update started.]
Invalid custom flash image format.
Finished at local time: [12.21.15 11:05:06]
WorkID: 8411794