>>921
1. Boot into recovery (You need to allow system partition modification to be able resize /system in recovery).
2. Backup your data & Move your files from flash to your PC.
3. Flash repartition pack zip.
4. Do the actions asked by repartition pack (go to Terminal in ordinary recovery and input word that pack will tell you. Everything else will be done automatically).
5. Phone will reboot into recovery.
6. Install TWRP from below (it is build with support of new partitions layout and sizes. It can be differed from official TWRP by next format 3.x.x-1 UA).
7. Format everything. (mount errors will not affect formatting!)
- In TWRP: Wipe > Format data
- Type yes
- Once this completes go to: Wipe > Advanced Wipe
- Tick all the boxes and wipe. There should be no further mount errors.
8. Install ROM which you like.
9. Enjoy better flash partition layout.