Spend now nearly a day with testing and installation of Lineage 16.1. Came from encrypted 14.1. which was updated to 15.1. Encryption after update to 15.1 still working.
Made a complete TWRP backup prior to starting next steps.
Can report as follows in short without details and hope that I remember to all steps – all steps made under Ubuntu:
- Additional backup under Ubuntu with:
sudo adb backup -apk -noshared -all - f backup.ab.
Worked and created „backup.ab“ file
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Formated under TWRP „data-partion“
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TWRP was still available after reboot, but of course all data and encryption were lost.
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Updated TWRP to twrp-3.3.0-0
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Installed via TWRP lineage-16.0-20190520-nightly. Did not yet try to encrypt but tried to install data back with ADB command :
„adb restore backup.ab“
No success! There was no failure report but after procedure there were no backed-up apps and no further other data on the phone. Phone was as it was before.
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Encrypted phone. Encryption worked without problems and phone rebooted directly and to TWRP. TWRP now suddenly shows data-partion with „0 MB“ despite the fact that there were some data. Furthermore, back-up of data not possible. All other partitions were backed-up.
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Made again a backup with ADB as TWRP does not backup data-partion. But backed up only APPS installed additionally with „adb backup -apk -noshared backup.ab“ Attention: Prior USB-debugging necessary!
FP2 asks now for password as the phone is encrypted and saved apps under „backup.ab“ on my computer.
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Deleted the newly installed APPS again.
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After „ sudo adb restore backup.ab“ and answering passcode question there was no failure notification but as above no apps returned.
Summary for my tests:
a) TWRP and Android 16.1. successfully installed
b) Android 16.1. can be encrypted and phone boots to recovery and also restarts but
- no backup of „data“ possible (neither with TWRP nor under ADB). Other partitions seem to be backed-up. I do not want to try Titanium as I have no Google and do not want to root.
If nobody finds a better solution I have only 2 options:
Option 1: Use encrypted phone without backups
Option 2 : Use unencrypted phone with backups and hope that there will be any solution in future.