Update August 21 2025: I switched from nextcloud to own cloud and just backup using the webdav tool
As in the last 3-4 summers, I spent a day updating my phone: deleting old files, backing everything up to a second drive, and reinstalling the OS after a factory reset. The OS reinstallation used to take a lot of time, but this time I was really fast—it only took me about half an hour.
Nextcloud
I’ve been backing up my phone to my Nextcloud server for over a year now, but I never needed it until now. After the last reinstall, I tested it for the first time. There were some problems, but actually not many, and it worked better than I had anticipated.
Android
The phone was running LineageOS 20. I went to the backup section, created a new vault, and saved the key somewhere in my room. At first, I didn’t check the experimental box for backing up all my data, but for the sake of the experiment, the last backup before the reinstall was done with this feature enabled.
Overall, the experience was rather smooth. The only annoyance was that turning the device off during the backup process would kill the ongoing backup. I guess this is because I always have battery saver enabled, which stops all processes when the phone goes to sleep. Since the backup doesn’t take long (about 5-10 minutes), it’s not that big of a deal.
After the Reinstall
I always factory reset the phone before a reinstall. Technically, it should work without this step, but since I want my phone to be clean, I enjoy the added benefit of a higher chance of success.
After the reinstall, the LineageOS startup activity, along with many other requests, asked me if I would like to restore the phone from a backup. It recommended doing it via WebDAV, which Nextcloud is capable of, but it also showed a Nextcloud option. However, the Nextcloud option was grayed out and unresponsive, so I just went on with the setup.
From the normal start window, I went to the settings app and backup, but I couldn’t just load a backup. I only had the option to create a new backup password key. Maybe a restoration was possible after this setup, but I was too lazy to save the auto-generated password key and repeat it on the next setup page. So, I continued searching for how to restore a backup from Nextcloud without doing this.
I now have the phone set up again, and I don’t think creating a new key to restore a backup would have worked. The backup menu is now unlocked, but there doesn’t seem to be a restore button for the whole OS. I wonder how they intended this feature to be used because the way I did it definitely wasn’t consumer friendly.
Restore from Startup Activity
The one place I had seen the option to restore the backup was in the startup activity. Back then, the Nextcloud option was grayed out because it was not yet installed on this OS. I mean, how could it be? The startup activity opens when you start the OS for the first time, and it’s hard (though very possible) to install an app before ever logging into the OS.
Thankfully, someone else had already written about it in this article.
So, I installed the Nextcloud app, connected it, and enabled developer options with root login enabled. Then, I connected my phone to the computer and started ADB with root:
sudo ./adb root
With a root shell (doesn’t work without root due to permission problems), I was able to start the startup application again, conveniently directly at the page where I could restore a backup:
am start-activity -a com.stevesoltys.seedvault.RESTORE_BACKUP
Restore
I had quite the shock while selecting the backup because the interface estimated the size of the backup at 0 bytes. This must have been a bug, as restoring all the amazing stuff from 0 bytes is quite a challenge.
What Was Backed Up
With all the options discussed above enabled, the backup had saved all the apps that were installed. Not just the names, but it seemed like the whole APK, because it was able to install paid apps without problems. It even installed apps I swear I had deleted a while ago. The restore started by installing these. I guess the backup also included system-level apps like the “Window Manager” and “Power Manager,” but these failed to reinstall.
It then proceeded to restore the data from a lot of apps, applying the backed-up data to them.
It ended with a prompt that it was now going to restore image files from the old backup, but I could do other stuff on the phone while it was doing this. Since I saw that it was downloading files from Nextcloud, I decided not to risk losing communication and just left the phone on the restore screen.
Backed-Up Configuration
I was really surprised by how well the backed-up configurations worked. System-level stuff did not, so I had to redefine the default apps and power settings. However, Nova Launcher, Hacki, and Aegis worked flawlessly. Other apps, like WhatsApp (I guess this app is just bad), did not save their config.