Can I backup my current system in recovery mode (Z Pro original Recovery, not TWRP)?
I followed the instructions below..
1. Press and hold the volume-up and power buttons together until your phone restarts in the boot selector mode.
It needs about 10 seconds or a little bit less if your phone was already powered off.
2. Here you can move with the vol-up button and select an item with vol-down.
Select Recovery.
...but unfortunately this did not work.
I am surprised, however, that the backup of the user data needs about 25.000 MB of disk space.
The internal memory is only 8GB in use.
For my other smartphones with TWRP, a maximum of 3.500 MB is required.