First thanks a lot for the amazing work which will allow recycling some old Samsung SII !
I got recently a i9100 to play with. I first did a factory reset on the stock ROM, on Android 4.1.2
And trying to flash to Android 12.1
Finally Done. Steps:
1. Flash PIT
i9100-LOS-19.1.pit
2. Flash via odin File tar
i9100-LOS-19.1_android-12.1.0_r2.tar
3. Phone go only download mode or recovery.
4. Put
lineage-19.1-20220613-UNOFFICIAL-i9100.zip in microsd
5. Reboot in recovery TWRP and flash file from sd.
6. Reboot in recovery TWRP and full wipe
7. Reboot system and it's all ok.
8. Now flash gapps
Thanks a lot for all support
this is one of the key msg in the whole flashing procedure, but likely still need a bit more details for newbies.
I used Odin to flash my phone as stated in the first page, so as steps 1 and 2.
And ended as well in the 'download mode'.
I did it twice, same story.
Then, I followed your step, with the zip file in microSD.
5. I used the key combination home+volUp+start which started TWRP, I chose the 'install zip' stuff.
I got a few errors there: the partitions could not be mounted properly:
failed to mount /cache (invalid argument))
failed to mount /data and unable to find crypto footer.
Updating partition details....
failed to mount /cache (invalid argument)
failed to mount /data (invalid argument)
failed to mount /preload (invalid argument)
...done
failed to mount storage
failed to mount /data (invalid argument)
full SELinux support is present
unable to mount /data/media/TWRP/.twrps
WTP Enabled
Installing zip file /sdcard1/lineage-19.1-20220613-UNOFFICIAL-i9100.zip
Umounting System...
Target: samsung/GT-I9100/GT-I9100:4.1.2/JZ054K/
I9100XWMS2:user/release-keys
Patching system image unconditionally...
I first let it reboot, it started with the lineAgeOS logo but did not move for 20 min.
6. I removed the battery, started again in TWRP, did the wipe per default. What is meant here with '
full' wipe?
7. During the reboot, the LineAgeOS logo appeared again, and then it switched to a "Encryption unsuccessful" screen, with a button "Erase all data" I can NOT press as if the touchscreen will be inactive.
Thus, I just restarted the phone. But back on this "Encryption unsuccessful" page.
The phone is still recognized from my PC, but using adb
> adb devices
List of devices attached
0019ab5e42017e unauthorized
while it says 'recovery' when started in TWRP. And used to be the correct 'device' before I started the whole process.
What should I do now to fix the flash?
EDIT: looking a bit further in the TWRP options, no wonder that I got the above errors: my 'data' partition is not setup properly, set to size 0 MB.
I however can't resize or repair it.
But could format it and is now 12591 MB as expected from the pit file
The 'Cache' partition is 74MB, as from the pit file
The 'System' partition is 2015 MB, I suppose it corresponds to the FACTORYFS
'Preload is 7 MB, so for the UMS or HIDDEN partition.
'Internal storage' is invalid
So for the point 5, the 'format data' is the key.
Now my i9100 is now setup with LineAgeOS

However, it is slow...
8. I could then install the BiTGApps-arm-12.1.0-v2.3-CORE.zip via the 'install zip' of TWRP
Edit2: specially after the BitGApps install, the smartphone is so sluggish that it is barely usable.
As already mentioned by one comment, the "battery manager" is slowing down the whole, so the first step is to disable the battery manager. And disable the gestures navigation, also slower than the buttons.
Nevertheless, the GooglePlay does not work properly: it keeps saying 'you are offline' while the browser is working fine. I am only on Wifi, tried both the 2.4Ghz and 5Ghz.