This comprehensive guide outlines the exact, step-by-step procedure to manually roll back an Arch Linux system utilizing systemd-boot, Unified Kernel Images (UKI), Btrfs subvolumes, and Snapper when the system is unbootable, followed by fixing the missing kernel modules and broken Snapper bindings entirely offline.
When your system is completely broken or stuck on a black screen, you cannot use automated tools. You must boot into any Arch Linux Live USB and manually swap the subvolumes using the Btrfs command-line tools.
Once inside the Live USB terminal, create a mount point and mount the root of your Btrfs partition (subvolid=5) to access all subvolumes.
(Replace /dev/nvme0n1p2 with your actual root partition).
mount /dev/nvme0n1p2 /mnt -o subvolid=5
List the contents of your subvolumes to see your current root (@) and locate where your Snapper snapshots are kept.
(If your .snapshots directory is nested inside @, it will be accessible under /mnt/@/.snapshots/).
ls /mnt/@/.snapshots/
Identify the snapshot number you want to revert to (e.g., 116).
Rename your current broken root subvolume to something temporary like @_bozuk so you don't lose any files and can steal working drivers from it later.
mv /mnt/@ /mnt/@_bozuk
Snapper snapshots are read-only by default. To make it your new working root, you must create a writable snapshot clone named exactly @ from the target backup path:
btrfs subvolume snapshot /mnt/@_bozuk/.snapshots/116/snapshot /mnt/@
The subvolume swap is complete. Unmount the drive and reboot into your main machine.
umount /mnt
reboot
After booting into your rolled-back system, you will notice a complete loss of Wi-Fi/Ethernet and sound, along with slow boot times. This is the "Time Paradox" effect: your system booted with the latest kernel, but your old 09:00 AM snapshot does not have the newer driver files (/usr/lib/modules/) yet.
Let's copy them from the broken system entirely offline:
Open a normal terminal on your host system:
sudo mount /dev/nvme0n1p2 /mnt -o subvolid=5
Clone the newer driver folders from your saved @_bozuk partition directly into your current active root (@):
sudo cp -r /mnt/@_bozuk/usr/lib/modules/* /usr/lib/modules/
sudo umount /mnt
sudo reboot
Result: Boot times will instantly drop to seconds, and network/sound drivers will be fully restored.
Because the original .snapshots directory was physically inside the old root subvolume, it is now trapped inside @_bozuk. Running pacman will throw an IO Error (.snapshots is not a btrfs subvolume). Let's return it to its proper place.
sudo mount /dev/nvme0n1p2 /mnt -o subvolid=5
Your new root generated an empty, standalone folder named .snapshots. Wipe it out so we can replace it:
sudo rm -rf /mnt/@/.snapshots
Move your actual snapshot history back into the active root layout:
sudo mv /mnt/@_bozuk/.snapshots /mnt/@/.snapshots
sudo umount /mnt
sudo snapper list
Result: Your entire snapshot timeline will load flawlessly without errors.
Since we manually pasted raw files into system directories, the package manager and the dynamic kernel module tree must be synchronized to prevent future upgrade conflicts.
Force pacman to overwrite the manually copied module files so they are properly tracked by the system database again:
sudo pacman -S linux-zen linux-zen-headers --overwrite "/usr/lib/modules/*"
(Adjust linux-zen to your specific kernel flavor).
If your GPU drivers fail to register during the upgrade step because files already exist, force DKMS to overwrite and stamp them officially:
sudo dkms install nvidia/[driver-version] -k [kernel-version] --force
Example: sudo dkms install nvidia/610.43.02 -k 7.0.13-zen1-1-zen --force
The absolute final step is to lock all these kernel fixes and drivers natively into your UEFI boot partition by rebuilding your unified binary (.efi) image.
sudo mkinitcpio -P
Once the terminal outputs:
==> Creating unified kernel image: '/boot/EFI/Linux/arch-linux-zen.efi'
==> Unified kernel image generation successful
Your modern Arch Linux system is officially 100% stable, fully operational, and fully updated.
To completely avoid using Live USBs and TTY commands for rollbacks, install btrfs-assistant from the AUR.
As long as your system boots into a terminal or desktop interface, you can simply launch btrfs-assistant, navigate to the Snapper tab, select any historical restore point, and click Restore. It handles the subvolume cleanup and configuration linking automatically behind the scenes in milliseconds.