ONE M7 Google Edition Update Problem - Sufficient Space - Couldn't Download

hi
i want to update my phone 4.4.4 to android L , 5.1 (Official)
but every time show this error Insufficient Space ... :confused:

i delete Google service & Google play , cache / data , But problem is still.
i clear cache with CM.
and uninstall all apps
delete all google apps cache / data
change google account
reset & more , But problem is still !
:(

finally i reset factory my device and now just show this error :
Couldn't Download
* No root , internal memory is more than 20 gig free , i want to use the official update method (No OTA)

Please help
Thanks.