Upgrading from Android 8 to 9 will earse the datas?

[hegeds]

Hi guys, I just saw that the Android 9 stable rom came out for mi mix 2 and I wanna upgrade to it, but I don't know if upgrading will earse all the data including apps, apps data...
If so, do you know any way to help fasten up the "recovery"?

Thank

 

[ToLive]

Make a full backup to PC and check it. I have to erase data even with change Miui (android 9) to AOSP (android 9). Upgrade 8 -> 9 should be ok, but reverting 9 -> 8 = format data.

 

[hegeds]

Make a full backup to PC and check it.

What do you suggest to use for the back up?