There is no OTA package for system downgrade. If you want to return to any previous ROM version you have to flash the complete ROM using SPFT tool. Don´t forget to flash everything, also I would advise to preform factory reset. When upgrading from Andoid 6 to Android 7 it is recommended to use OTA, because due to a bug you may lose your IMEI numbers whiile flashing Nougat ROM by SPFT.
Edited by GamingMonster at 2017-7-14 14:22 \n\nThe Umidigi mobile YouTube channel told me they would release an update yesterday...
Edit: I don't understand it: You can't upload the update for the Z becaus you have very slow WiFi on vacation, but you can release a update for the Z Pro (while you can't for the Z)?!?
Sorry if it's unrespectfull, but I doesn't understand it....
Ben already said in one of the threads that the official way to update your phone is via the OTA update. AFAIK no OTA update was released yet, thus no SPFT image can be posted. Him being on vacation has nothing to do with it. The Z pro might share hardware with Z and most likely they share codebase, but they are still two different phones. Once the update for the Z is out, the links will be posted eventually.