Backing up your Firefox Nightly profile on Android

2024/11/13

It’s the same trick as last time.

Download v1.0.1.

Install it.

adb install -r -d firefox_preview-1.0.1.aarch64.apk
# don't launch this early version

Back up.

adb backup -f fenix-backup.ab org.mozilla.fenix

Then update back to the current version.


To restore, install the old version that allows backup, restore the backup, then install the

adb install firefox_preview-1.0.1.aarch64.apk
# don't launch this early version

Restore.

adb restore fenix-backup.ab

Then update back to the current version.


If you need to extract something, some guy on the Internet said that, as long as you don’t set a password, it’s a custom 24-byte header followed by zlib compressed tar file.

tail -c+25 fenix-backup.ab | openssl zlib -d | tar -xv

I also see people saying their openssl doesn’t have zlib, and they have various other ideas how to decompress it.


Interesting that Fenix had a version that allowed backup, years after they disabled backups in its predecessor, Fennec. But whatever, the change is this commit referencing some unseen force that restores the backup. GitHub indicates that this change is present all the way back to v1.1.0-rc.1 (at this time the versions must have been in a separate continuum from the rest of Firefox), so that’s how I found v1.0.1 without it. There were only ever 5 builds before this change, so we’re lucky they exist at all.

Users on beta and release channels I think have no such luck.

My last post was about either Substances that are liquid but that are considered dry or Resources in Diablo 4, a 40-hour impression. Find out which.