I'm about to switch my outdated Samsung tablet and smartphones to LineageOS. But I want to make a backup of my device, including the OS and everything, in case something goes wrong and I need to flash the original OS back into the device.

How do I proceed? I think I need to do a Nandroid backup or something? Is that correct?

You can't. Most apps resist being backed up. Seedvault is the most often recommended backup tool for Android, but it only backs up apps that allow themself to be backed up. You'll get your SMS messages, call history, contacts, and files visible in file manager. But most apps, and almost all proprietary apps will not have their app data backed up.

https://www.samsung.com/us/support/answer/ANS10002780/

Or root it and use your tool of choice. Nandroid backups haven't worked for years.

May I ask what the current tools of choice are for newer Androids? I currently still back up my apps using TitaniumBackup and I can even restore them, they just need manually fixing SELinux permissions on the restored files via a root shell. But I assume there are better alternatives out there nowadays.

Generally not possible either. Unlocking the bootloader always wipes the phone. So unless it's already unlocked, or it can be unlocked with some sort of exploit instead of using fastboot, it'll be worse than a (bad) normal backup.

On the flip side, so many apps these days keep data local, but the master copy is all on their servers.

You want to back up SMS, photos and any downloads, documents, files or data. It pretty much needs to be manually done.

1. there's "Samsung Smart Switch", their official backup tool. It sorta works but many settings and apps won't be properly backed up. this is the best you can do officially.

2. if you're on a slightly older OS version, you may be able to use a recent Linux kernel exploit to temporarily root the device. (see: Root My Galaxy) then you can use a tool like Swift Backup or NeoBackup. (you can't use the official method of unlocking bootloader and doing nandroid backup, because unless you already have an unlocked bootloader, the unlock process mandates factory reset and wipes your data)

i've heard good stuff about Swift Backup and Neo Backup. but personally i'm on android 8 and 11, still using titanium backup since it works well enough.

The last few times I've used Swift Backup and it served me well. Seems less complicated than Seedvault.

Thanks, I'll take a look.

If you ever want to restore on a newer Android (at least I needed this on lineageos with android 15 or 16), you need to fix SELinux permissions on the data files. This is the script I use after restoring, but before starting the app. Maybe it helps.

#!/bin/bash
# Fix restored file permissions by copying permissions from parent directory
set -euo pipefail

if [ "$#" -ne 1 ]; then
    echo "Usage: $0 /data/user/0/<appname>"
    exit 1
fi

APP_DIR=$1
SEL_CONFIG=$(getfattr -d -n 'security.selinux' $APP_DIR | grep security.selinux | cut -d'=' -f2- | tr -d '"')
find $APP_DIR -exec setfattr -n security.selinux -v "$SEL_CONFIG" {} \;

I don't think you can do the entire phone but you can do through each app and see which ones allow you to backup data and settings. If you have pictures you can use something like immich to back that up. If you need to back up SMS/MMS/phone logs there's sms import/export on Fdroid.

You can also plug your phone into a computer and download any folders you have data in.

I don't think I really care about the apps. It's more about the OS/Rom. I've downloaded the last rom update from some shady 3rd party site, but I don't trust it. I can't download the official images from samsung anymore. So I'd rather do a backup that I can roll back to if lineage fails.

Thank you. That's probably what I'm looking for.

It's not really about the data. It's more about the OS. I want to be able to roll back to the original image if Lineage OS fails.