Nandroid backup problem on Android pie

[sandeep_kumar]

I have flashed Nitrogen OS, Colt OS and NLOS OS. All pie based ROM on my 3t.
While switching from one ROM to other I always take the nandroid back up and save it to my PC.
My device is decrypted, and I was using NLOS 16.

Last night, I tried to flash to flash baikal OS but unfortunatley I got bootloops so I decided to restore the latest nandroid back up of NLOS 16.
While restoring ,I was aware that NLOS is 5.0.8 fw based ROM as of now, so I first flashed the firmware then I started restoration, after hitting reboot system; phone went to bootloader mode. I again tried but in vein.

So I decided to take the nandroid back up of COLT OS with similar steps but again the phone showed the bootloader screen.

Now, finally I tried Nitrogen OS nandroid back up. It booted successfully.

So I want to know, what is causing the trouble in NLOS and COLT OS nandroid back which force the system to go to bootloader screen. I recall when I was on oreo ROM but encrypted, I could restore the nandroid back up easily by just flashing the recommended firmware first and then restoring.

Is it due to the fact that my device is decrypted and I am taking nandroid back up of sellinux enforcing builds of NLOS and COLT OS .
afaik Nitrogne OS use the sellinux in permissive mode while others are all enforcing.

 

[mvalda01]

I'm pretty sure you took Nitrogen backup with latest TWRP and the other two backups with the second-last TWRP which had problems backupping and restoring. Nothing to do with encryption.

 

[sandeep_kumar]

I'm pretty sure you took Nitrogen backup with latest TWRP and the other two backups with the second-last TWRP which had problems backupping and restoring. Nothing to do with encryption.

No, I used the same TWRP 3.3..0-1 for all ROMs.
I was using NLOS which I did flash through TWRP 3.3.0-1 and took the back up first then I proceeded to flash other ROM but restoration of the same NLOS ROM was unsuccessful.

 

[Dirk]

No, I used the same TWRP 3.3..0-1 for all ROMs.
I was using NLOS which I did flash through TWRP 3.3.0-1 and took the back up first then I proceeded to flash other ROM but restoration of the same NLOS ROM was unsuccessful.

So mvalda was correct. You are using the version of TWRP that couldn't restore /system from your backup. (The System Image option would have worked). The latest build, 3.3.1-0, fixes that issue.

Another way to get the backup working on the old build was to restore the backup and immediately dirty flash your ROM again.

Update your TWRP to latest and take a backup.

Edit: Flashing Firmware before restoring a backup is pointless. The backup will immediately overwrite it.