Database Info

[Q] How to backup my software?

Hello. Currently, I am using RCMix S 2.7 and i thinking this is most stable and great rom for Desire S. I setup my mobile(applications, widgets, settings). However I would like to test new roms. How I can backup my customized software? I did backup in ClockworkMod Recovery and size of my software is 1.05Gb. Is this enough? How to make restore? Do i need to choose only restore or format something first?

Use Google sync for your Contacts and Calendar items (HTC Sync + M$ Outlook is also a good combination but you can use it only on Sense ROMs)
Download and install free Titanium Backup from the Market to backup your applications and settings (you can backup even your homescreen arrangement (all shortcuts and widgets) and restore them in one click. The backup itself is not taking too much space. My advice is when switching to ROM with different Sense/Kernel/Android version do not restore setting, it can mess up your new installation, restore just the apps and take the time to configure everything again.

I also test new roms all the time. My technique of back up is this.
1. contacs = back up using google. sync with your google account.
2. sms = i use 'kAmMa's BackupSMS'
3. Application = I only backup downloaded apps using Astro file manager.
For me titanium back up is a bit complicated.
to restore i always do this order
first use the filemanager in the rom - browse to backup folder and install astro file manager.
than use astro file manager and install all the other application that you back up
than setup google account and your contact will be downloaded automatically from internet.
than restore sms using the kamma's backupsms.
its done. I spend about 30 minutes for this. This is my way of doing things. If you like you can follow this way.

What You thinking about it:
How To: Backup or Restore via Nandroid
Nandroid allows you to create a complete system image of your device and stores it to the SD Card on your phone. Making one is very simple but there are a few prerequisites.
1. A rooted Android phone
2. A custom recovery that supports Nandroid (ie: Amon_RA, ClockworkMod, Etc.)
3. A MicroSD card that has enough space for a system image.
A complete image can range from 75-400 MB.
Please follow this link for instructions: http://forum.xda-developers.com/wiki...r_via_Nandroid

Ok, I got your point. You want to preserve you current ROM in the way it is now in case that you would like to go back to it.
In this case before restoration you have to follow the same steps like in installation of a new ROM:
Wipe all (system, data, cache)
Restore

Thanks a lot!

amidabuddha said:
Ok, I got your point. You want to preserve you current ROM in the way it is now in case that you would like to go back to it.
In this case before restoration you have to follow the same steps like in installation of a new ROM:
Wipe all (system, data, cache)
Restore
Click to expand...
Click to collapse
If you just want to simply restore one of your previously taken Nandoird backups then there is no need to wipe anything in advance as the restore will overwrite all partitions.
While saying that every time that I've performed a restore for safety's sake I always then wipe cache and dalvik cache before booting the restored ROM.

{TIP] Restoring TWRP backup after complete data wipe

Ok so I had a problem recently and found a solution which might help. I googled, looked in this and a bunch of other android forums and didn't find the solution I had, so maybe my way is not the best way to do it - but it solved my problem maybe it might help you.
When I flash a new rom with a different framework to the rom I'm currently on I take care to make a full TWRP back-up of my current system move that across to my PC, then proceed to wipe everything on my phone, data, system, factory reset and numerous cache and dalvik wipes. (I use the Awesome scripts superwipe and kernel cleaners which do the trick really well).
Anyway recently I installed a rom which really didn't work for me, so i wanted to get back to where I was before I installed it. I booted into TWRP cleaned the data, system factory reset wiped the caches. I mount my PC move my nandroid across to my SDcard and go to restore. But of course TWRP looks in the restore folder for the backup and I have wiped this so the file structure does not exist.
So after telling myself what an idiot I was for not remembering what the file system was, here's what I did:
1 - Stopped panicking!
2 - Ran the back-up utility in TWRP - this recreates the file structure for the back-ups and places a back-up of your empty system in the folder
3 - Move the original full back-up I placed in the empty SDcard into the file system next to the empty back-up I'd just created
4 - Go to restore and the full back-up is there. Swiped to restore it and my One S is back to it's old self
Lessons learnt: Don't panic - there is an answer. Just think about it.
Good luck!

Or you could just copy the whole twrp folder to your hdd. thats what I do anyway and restore without a problem.

Yep that would have prevented me ending up in that predicament for sure.
So would not flashing roms. The point of the post is really about what to do if you find yourself in that situation and the value of keeping a cool head and thinking through a solution rationally, using your own resources.
The way I see it is: it's my mess I got into it, how am I going to solve it....
Sent from my HTC One S using xda app-developers app

Lost my Backup
Good advice which I'm trying to follow but my TWRP Recovery cannot see the TWRP ROM Backups that I created with ROM Customizer which ROM Customizer has placed in the folder
/data/media/0/TWRP/Backups/4df1bd936aae7f4b
but when my Samsung Galaxy S3 i9300 is in Recovery Mode it is obviously looking somewhere else........I just can't figure out where because then I can just move the backup to where ?Recovery Mode is looking.
Anyone any ideas please?

matrixmainframe said:
Good advice which I'm trying to follow but my TWRP Recovery cannot see the TWRP ROM Backups that I created with ROM Customizer which ROM Customizer has placed in the folder
/data/media/0/TWRP/Backups/4df1bd936aae7f4b
but when my Samsung Galaxy S3 i9300 is in Recovery Mode it is obviously looking somewhere else........I just can't figure out where because then I can just move the backup to where ?Recovery Mode is looking.
Anyone any ideas please?
Click to expand...
Click to collapse
Do what the op says and do a backup and you will know where to put it.
Sent from my HTC One S using Tapatalk 2

Plz HELP!!!
ACtually im in deep deep trouble please i would be really grateful to the person who helps me. OK so last night i flashed cyanogen mod10 on my htc one x and when i did everything booted the boot.img and all i factory reseted from cm10 because it gave me the error that unfortunately android.process.phone has stopped nevertheless now everythings gone and no supersu root file is gone which is obvious that i dont have root now. Plz tell me how to go back to my factory settings with htc sense on it now i just want my phone back, i did another factory reset wiping off the rom but it says no OS installed and it gets stuck on htc quitly brilliant screen plz plz plz plz help me any one plz.

abdullah.imran2158 said:
ACtually im in deep deep trouble please i would be really grateful to the person who helps me. OK so last night i flashed cyanogen mod10 on my htc one x and when i did everything booted the boot.img and all i factory reseted from cm10 because it gave me the error that unfortunately android.process.phone has stopped nevertheless now everythings gone and no supersu root file is gone which is obvious that i dont have root now. Plz tell me how to go back to my factory settings with htc sense on it now i just want my phone back, i did another factory reset wiping off the rom but it says no OS installed and it gets stuck on htc quitly brilliant screen plz plz plz plz help me any one plz.
Click to expand...
Click to collapse
1. wrong forum, if you have a one x device
2. calm down
3. relock your bootloader (fastboot oem lock)
4. download and run latest ruu for your phone (search for a suitable one for your cid and carrier if you are branded)
5. you also can flash a custom sense based rom, which gives you sense back (viper one s or trickdroid or android revolution hd)
6. if you want to flash one of these,dont forget to flash the boot.img too
7. before flashing a rom, wipe system, data and cache 3xtimes to be sure you do a clean install

Thanks Man
ATSPerson said:
Ok so I had a problem recently and found a solution which might help. I googled, looked in this and a bunch of other android forums and didn't find the solution I had, so maybe my way is not the best way to do it - but it solved my problem maybe it might help you.
When I flash a new rom with a different framework to the rom I'm currently on I take care to make a full TWRP back-up of my current system move that across to my PC, then proceed to wipe everything on my phone, data, system, factory reset and numerous cache and dalvik wipes. (I use the Awesome scripts superwipe and kernel cleaners which do the trick really well).
Anyway recently I installed a rom which really didn't work for me, so i wanted to get back to where I was before I installed it. I booted into TWRP cleaned the data, system factory reset wiped the caches. I mount my PC move my nandroid across to my SDcard and go to restore. But of course TWRP looks in the restore folder for the backup and I have wiped this so the file structure does not exist.
So after telling myself what an idiot I was for not remembering what the file system was, here's what I did:
1 - Stopped panicking!
2 - Ran the back-up utility in TWRP - this recreates the file structure for the back-ups and places a back-up of your empty system in the folder
3 - Move the original full back-up I placed in the empty SDcard into the file system next to the empty back-up I'd just created
4 - Go to restore and the full back-up is there. Swiped to restore it and my One S is back to it's old self
Lessons learnt: Don't panic - there is an answer. Just think about it.
Good luck!
Click to expand...
Click to collapse
Thanks Man, been stuck in TWRP for about two hours now, thought I soft bricked my Droid Dna forever. I had a backup, and adb pushed it to the /sdcard directory, but it wouldn't show up in the restore section. This empty-backup method worked fine. Thanks, you saved me $400.:good:

Saved my HTC One!
ATSPerson said:
Ok so I had a problem recently and found a solution which might help. I googled, looked in this and a bunch of other android forums and didn't find the solution I had, so maybe my way is not the best way to do it - but it solved my problem maybe it might help you.
When I flash a new rom with a different framework to the rom I'm currently on I take care to make a full TWRP back-up of my current system move that across to my PC, then proceed to wipe everything on my phone, data, system, factory reset and numerous cache and dalvik wipes. (I use the Awesome scripts superwipe and kernel cleaners which do the trick really well).
Anyway recently I installed a rom which really didn't work for me, so i wanted to get back to where I was before I installed it. I booted into TWRP cleaned the data, system factory reset wiped the caches. I mount my PC move my nandroid across to my SDcard and go to restore. But of course TWRP looks in the restore folder for the backup and I have wiped this so the file structure does not exist.
So after telling myself what an idiot I was for not remembering what the file system was, here's what I did:
1 - Stopped panicking!
2 - Ran the back-up utility in TWRP - this recreates the file structure for the back-ups and places a back-up of your empty system in the folder
3 - Move the original full back-up I placed in the empty SDcard into the file system next to the empty back-up I'd just created
4 - Go to restore and the full back-up is there. Swiped to restore it and my One S is back to it's old self
Lessons learnt: Don't panic - there is an answer. Just think about it.
Good luck!
Click to expand...
Click to collapse
I'd just like to say a MASSIVE THANK YOU for this post! I had a major issue and thought I'd lost my 1-day old HTC One (M7). I wasn't so much panicking as I knew i'd find a way, but a cold sweat had started to break!
The biggest lesson I can take from this is simply this... MAKE SURE YOU BACKUP YOUR ORIGINAL ROM BEFORE YOU DO ANYTHING! It's such an obvious thing, but without this simple step, I'd be in trouble right now as HTC haven't an RUU for my specific device yet (plus I'm on a Mac, making running .exe files more painful still)
What had happened was that as a result of a corporate email policy, I had to encrypt my device. I did this after flashing to a new ROM. Unfortunately after I had done so, the new ROM wasn't playing nicely with Exchange (using native HTC Mail app). Of course the issue here is that when you so into TWRP, you can't see the files to restore (because TWRP is opened before the device asks you for the passcode to decrypt... another learning!). To remove the encryption, I had no choice but to do a full format of the device, so I was basically left with a brick
Anyway, once again, thank you for this post, you just saved me AU$700!

Ok so, in not so many words, ur saying " to restore a nanBU":
1. Wipe: data factory reset/cache/ delvic
Wipe system (but not sure which one(s) cause I was used to cwm and it looks diff in twrp
2. Flash the Rom that the nanbu is based from
3. Flash the nanbu
4 reboot
It's this the correct way to restore a nanbu from a diff or upgraded rom?

So I had to do a complete restore of my default Samsung Note 2 Sprint L900 firmware after an unsuccessful Rom flash of Goodness Noteworthy 1.8.1 (numerous flashes and it wouldn't boot up past opening war video, just went to black screen and hung endlessly)
-OK so I then got back to root and installed TWRP 2.6 and I had already had several backup ROMS I saved to my computer. So I placed Goodness Noteworthy 1.7 in my backup folder in TWRP on my sdcard. I then reboot into TWRP recovery and go to restore and I can't see anything there. I have the sdcard mounted and checked and after clicking the restore button I'm not seeing anything. ? When I click install it see's everything on my sdcard ? I don't get it. What am I doing wrong.
---------- Post added at 01:20 PM ---------- Previous post was at 12:42 PM ----------
cheyennemtn said:
So I had to do a complete restore of my default Samsung Note 2 Sprint L900 firmware after an unsuccessful Rom flash of Goodness Noteworthy 1.8.1 (numerous flashes and it wouldn't boot up past opening war video, just went to black screen and hung endlessly)
-OK so I then got back to root and installed TWRP 2.6 and I had already had several backup ROMS I saved to my computer. So I placed Goodness Noteworthy 1.7 in my backup folder in TWRP on my sdcard. I then reboot into TWRP recovery and go to restore and I can't see anything there. I have the sdcard mounted and checked and after clicking the restore button I'm not seeing anything. ? When I click install it see's everything on my sdcard ? I don't get it. What am I doing wrong.
Click to expand...
Click to collapse
Solved.. Copied my backup stock ROM from the TWRP folder on the phone and placed it on the SDcard, then I placed my Goodness Noteworthy 1.7 backup rom I had that I had on my computer and copied and placed that on the SDcard in the TWRP folder next to the Stock Rom backup I made. Booted back into recovery and clicked RESTORE and I was able to see both the backup rom and the Goodness Noteworthy ROM. I then wiped and did a restore and I'm back in business.

:good:

cheyennemtn said:
So I had to do a complete restore of my default Samsung Note 2 Sprint L900 firmware after an unsuccessful Rom flash of Goodness Noteworthy 1.8.1 (numerous flashes and it wouldn't boot up past opening war video, just went to black screen and hung endlessly)
-OK so I then got back to root and installed TWRP 2.6 and I had already had several backup ROMS I saved to my computer. So I placed Goodness Noteworthy 1.7 in my backup folder in TWRP on my sdcard. I then reboot into TWRP recovery and go to restore and I can't see anything there. I have the sdcard mounted and checked and after clicking the restore button I'm not seeing anything. ? When I click install it see's everything on my sdcard ? I don't get it. What am I doing wrong.
---------- Post added at 01:20 PM ---------- Previous post was at 12:42 PM ----------
Solved.. Copied my backup stock ROM from the TWRP folder on the phone and placed it on the SDcard, then I placed my Goodness Noteworthy 1.7 backup rom I had that I had on my computer and copied and placed that on the SDcard in the TWRP folder next to the Stock Rom backup I made. Booted back into recovery and clicked RESTORE and I was able to see both the backup rom and the Goodness Noteworthy ROM. I then wiped and did a restore and I'm back in business.
Click to expand...
Click to collapse
Deleted comment

Hei guys,
Please help!!!! I tried to install MaximusHD 10.0.0 | JB 4.2.2 | Sense 5.0 on my HTC One s,i got storage issue. Now my sd card is just 48MB. I have installed TWRP v2.6.3.0 and i did backup before flashing room. I decided to do factory restore by TWRP and wiped OS from MY device.Now when i do backup i get failed error: not enough free space on storage. Total size of all data 203MB, available space 48 MB.I see my sd card on pc through TWRP, but i cannot make backup and even put any new rom into my sd card to flash it because of 48MB...Is it any chance to get back any OS on my HTC One s....?

This post might help
http://forum.xda-developers.com/showthread.php?p=47744972.
Sent from my One S using xda app-developers app

StifflerServices said:
Ok so, in not so many words, ur saying " to restore a nanBU":
1. Wipe: data factory reset/cache/ delvic
Wipe system (but not sure which one(s) cause I was used to cwm and it looks diff in twrp
2. Flash the Rom that the nanbu is based from
3. Flash the nanbu
4 reboot
It's this the correct way to restore a nanbu from a diff or upgraded rom?
Click to expand...
Click to collapse
EDIT: oops, somehow thought this was a recent post. Never mind
Not really.
If you are S-off,
Restore Backup,
Wipe Caches
S-On
Restore Backup
Wipe Caches
(if the rom you were previously on had a different Boot.img you will need to fastboot your boot.img) In the backup
Assumes you are not trying to restore a backup to 2.15 if you were just on 2.16. You will need to RUU + factory reset/clear storage for that.

I'm sry not sure what "RUU" means... Probably will remember once u tell me I'm sure. But Ya I kinda just winged it, didn't flash the Rom to do the NanBU and all went fine, which is odd cause on my S2 w cwm it out me in a boot loop and had to start over, but I think TWRP may be a diff setup when restoring nanbu's. But either way it's always nice to know and find a "step by step" guide to restoring NanBU's from previous / updated / or different ROMs. For noobs that was one of the confusing things to do due to lack of that info in threads or utube vids out there.

Got a question. I've made my backup files but restore shows nothing but storage... No files to chose, no more options to restore. Is it normal?
Sent with my One S C2 Sense 5 using Taptalk

brilliant!
ATSPerson said:
So after telling myself what an idiot I was for not remembering what the file system was, here's what I did:
1 - Stopped panicking!
2 - Ran the back-up utility in TWRP - this recreates the file structure for the back-ups and places a back-up of your empty system in the folder
3 - Move the original full back-up I placed in the empty SDcard into the file system next to the empty back-up I'd just created
4 - Go to restore and the full back-up is there. Swiped to restore it and my One S is back to it's old self
Lessons learnt: Don't panic - there is an answer. Just think about it.
Good luck!
Click to expand...
Click to collapse
you my friend, are a genius! I have been so screwed trying all kind of crazy stuff the last few days.
Brilliant! May I suggest you run for Pres of the Colonies.

metropical said:
you my friend, are a genius! I have been so screwed trying all kind of crazy stuff the last few days.
Brilliant! May I suggest you run for Pres of the Colonies.
Click to expand...
Click to collapse
From one Clash fan to another, thanks for the thanks ☺
¡La lucha continua!

is possible integrate apk's in firmware?

Hello everyone, I would like to restore often doing some apk in the rom that I have already installed, so if I do a factory data reset I find myself these integrated programs in the rom. I tried using Titanium Backup to create me an update zip but even if I flashed to restore the programs disappear. I remembered that you could do with titanium .... my questions are 2
1. if you can do it with titanium shown me step by step how to do?
2. there is a program to do these zip to flash that remain on forever?
thanks 1000

I don't know how to do that with Titanium Backup because i do not use it.
But you can make a flashable zip file of the (fresh flashed) firmware with cwm and integrate the apk's you want afterwards into the zip.
Maybe this gives you an idea.
Read Post 121 -123

myabc said:
Hello everyone, I would like to restore often doing some apk in the rom that I have already installed, so if I do a factory data reset I find myself these integrated programs in the rom. I tried using Titanium Backup to create me an update zip but even if I flashed to restore the programs disappear. I remembered that you could do with titanium .... my questions are 2
1. if you can do it with titanium shown me step by step how to do?
2. there is a program to do these zip to flash that remain on forever?
thanks 1000
Click to expand...
Click to collapse
Not tried on my Moto G (not really had the desire or need to deviate from stock), but on my rooted Tablet I use Titanium to
1 ) Integrate System App updates (e.g. Maps, Playstore etc) into the System partition - via the Batch Actions menu, under Move/Integrate.
2 ) Convert User Apps to System Apps - if you long press on the app on the app listing screen it shows a pop up menu - the last choice is 'Convert to system app'.

On my old phone I used RootExplorer and copied the file into the system and set the permissions. It might need a reboot after too. I didn't used it with updated apps but I prefer to keep things stock in that way.

[XT1032] CM 12 - Flashing TWRP v2.8.6.0 has caused bootloop

Hello,
XT1032 CM 12 latest nightly (I think)
I flashed TWRP v2.8.6.0 using their manager app. I entered recovery mode and everything seemed to work fine. I made a NANDroid backup then rebooted. Unfortunately the device was then stuck at the bootlogo and kept looping. I can still access recovery and fastboot but for some reason adb doesn't see the device, nor can my device's data be access under Windows 7. I don't recall if I had USB debugging on or not. I would like to try to backup a few files to my computer (the backup for instance) but I am unable to since I can't use adb as the device is not recognized. MTP through TWRP doesn't seem to work either. I do have the Universal drive pack installed already on Windows.
Any help would be greatly appreciated. Thanks for your time.

To start with, let's make sure the files you want still exist.
1. Boot into TWRP recovery
2. Go to "Mount" and check that your "Data" partition is selected
3. Go back and then go to "Advanced" and then to "File Manager"
4. Navigate around (maybe /sdcard/ ? Depends what you're looking for) and find the files you need
If you can't find your file, you'll need some more help. Let's say you do see your file. Do you have a USB-OTG cable? You could plug a USB drive into your phone and mount that. Then you could copy your file to that drive. If you don't have the cable you do have some other options, but let us know how far you get.
EDIT: I know I haven't addressed the problem of the bootloop at all. Many of those solutions involve wiping so we need to make sure you've backed up all the files you need first.

First of all thanks for the help. :good:
I've been trying to find a solution and in fact flashing CWM worked. I was able to adb pull all the files and make a backup.
I backed up the content of the sdcard. I tried restoring the CWM nandroid with data only so it did reinstall the apps but unfortunately all their data and settings are gone. Making a full restore just goes back to bricking. So I have the nandroid and the data manually backed up to a computer but no idea how to restore it.
I've tried pushing the nandroid back to /mnt/shell/emulated/clockworkmod/backup after an unsuccessful restore but now it doesn't even work. (protocol failure, the push command fails)
honestly at this point I think the best solution is just to make a clean install. In fact it would be a good idea to just reset the whole phone and start with a clean slate with CM13 including wiping system files and maybe manually restore some key files and configuration (I've got all the .com files of relevant apps)
Do you know how to do that? :laugh:

frustratedwhiteman said:
First of all thanks for the help. :good:
I've been trying to find a solution and in fact flashing CWM worked. I was able to adb pull all the files and make a backup.
I backed up the content of the sdcard. I tried restoring the CWM nandroid with data only so it did reinstall the apps but unfortunately all their data and settings are gone. Making a full restore just goes back to bricking. So I have the nandroid and the data manually backed up to a computer but no idea how to restore it.
I've tried pushing the nandroid back to /mnt/shell/emulated/clockworkmod/backup after an unsuccessful restore but now it doesn't even work. (protocol failure, the push command fails)
honestly at this point I think the best solution is just to make a clean install. In fact it would be a good idea to just reset the whole phone and start with a clean slate with CM13 including wiping system files and maybe manually restore some key files and configuration (I've got all the .com files of relevant apps)
Do you know how to do that? :laugh:
Click to expand...
Click to collapse
I'm not really a Nandroid expert, but I can take a few shots in the dark. When you did your backup you got a TAR file for System and one for Data, etc., right? Then you convert those to IMGs? If you upgraded and then restored the system backup I can see why that would result in a boot loop. Restoring the data image shouldn't cause such problems though. Is this what you've tried so far? You're right, though. The safest method is to manually restore the data of just the apps where you need that data, and do it one at a time. This would allow you to pinpoint what is causing the issue. Of course, I may have no idea what I'm talking about. I've never actually needed to restore a Nandroid backup! Hopefully someone with more experience there will chime in.

I thought to hell with it I went and solved the issue by installing CM13
Thanks for taking the time to help and see you next time

Backup methods, .win versus .img, when to use each type?

When I used payload dumper on the OTA for this device I ended up with 34 .img files. When I used TWRP to backup all the partitions from the OxygenOS I end up with 12 .win files. When I used dd commands to get copies of boot_a & boot_b and persist, I end up with .img files. When I used dd commands to get EFS backup I ended up with modemst1.bin and modemst2.bin.
I have all these back ups now but I'm not sure which type of file to use and when.
I have TWRP and Lineage on my 8T and they're working great. But I'd like to now restore OxygenOS, install the latest OTA, re-install TWRP, then install a newer version of Lineage. There's a good chance I'll slip up and have to recover my phone at some point and I'd like to know first if I'm better off trying to get TWRP booted and then restoring all the .win backups, or if I should just flash all the .img files from the payload dumper.
Can anyone offer some tips or explain the difference?

Look in TWRP thread. It mentions what partitions to backup (and restore) when changing ROMs.

Look in TWRP thread. It mentions what partitions to backup (and restore) when changing ROMs.
Click to expand...
Click to collapse
I've read through that thread and made a lot of notes, but I guess I'm just wondering at this point, since we have a fully-functional TWRP is it the case that as long as I have the .win files from the TWRP backup of boot, dtbo, super and data partitions that should be all I need?
Persist.img & Modemst1/2.bin & boot_a/b.img can be discarded? Or would you keep these on hand for other reasons?

FakeGemstone said:
I've read through that thread and made a lot of notes, but I guess I'm just wondering at this point, since we have a fully-functional TWRP is it the case that as long as I have the .win files from the TWRP backup of boot, dtbo, super and data partitions that should be all I need?
Persist.img & Modemst1/2.bin & boot_a/b.img can be discarded? Or would you keep these on hand for other reasons?
Click to expand...
Click to collapse
Persist and modem images presumably contain IMEI information, so better keep them somewhere safe. Boot_a/b.img can be discarded.

It's starting to make sense. Thank you for your explanation.

My phone had Lineage and TWRP installed and was running great, but I wanted to try out the backup and restore option of TWRP. So I backed up /data then used TWRP to restore the OxygenOS to the version I was using right before I installed Lineage. I restored OxygenOS to both slots and also I formatted /data.
After doing an minimal setup on OxygenOS, taking a quick look around to see if everything looked okay and rebooting to system a couple of times, I used TWRP to install LineageOS again. That seemed to work fine. I did minimal setup, took a look around, rebooted a couple of times, so far; so good.
I then followed the instructions from theincognito on Steps for backing up and restoring data in TWRP to restore the data partition:
It seemed to work fine, except I was never presented with a blank screen (a clue?) and the phone just booted to system normally. My apps and settings appeared to be restored BUT the 3-button system navigation icons (home/back/switchapps) were missing. So whenever I navigated away from the home screen there was no way to get back except to reboot the phone. It didn't matter if I switched to 2-button navigation or gesture navigation, none of it worked. So I guess the navigation options are all apps and those apps malfunctioned when /data was restored. Also, I could not enable Advanced Restart for the Power Menu. That's probably a system app, too. I didn't have a password on the phone at any time, or a SIM card installed. I know the TL;DR instructions in post #3 say that you should just reboot to system again if you have this problem, but doing so didn't fix the problem for me. I must have made a mistake at some point.
I ended up wiping the phone, doing a clean install of Lineage and setting up the apps and preferences the old-fashioned way.
I'd like to try this again to see if I can get it to work. Does anyone have suggestions of what went wrong?
Should I have tried restoring /data a second time before giving up and wiping the phone?
Does the fact I didn't get the expected blank screen after restoring /data have any significance?
Did the problem more likely originate with the backup process or the restore process?
Oh boy, it just dawned on me... Should I have also restored the backup of Boot/dtbo/Super? I assumed those wouldn't change if you were restoring to the exact same version of Lineage so I didn't bother with it.

I stumbled across a trick to get the restored data backup working again. I went to Settings --> Apps & Notifications --> App Info. Then I selected the option "Show System" from the list at the top with the 3 vertical dots. From the list of apps I selected 3-button navigation and then selected "force stop". After that, I rebooted and all the settings that were missing before were magically back in place, and both the Status Bar and the Navigation Bar were functioning and configured just the way I had them when I did the backup. I don't know anything about how system apps work so I can't explain why this helped, but I tested it twice with fresh installations of LineageOS and it worked exactly the same both times.
I should add that between this post and the one above from February 1st, I have re-installed Oxygen OS many times using old and new OTA zips, and installed Lineage OS several times, first on one slot then the other. And each time I've restored various back ups of LineageOS system files and LineageOS data files following the instructions, but always the result was a partial restoration of user configurations and missing status and navigation bars. I wonder that I'm the only person who found that booting twice after a data restore didn't bring back those menus. But hopefully if it happens to someone else they'll find this post and know what to do.