An unbootable system needs a working environment before repair can begin. Debian installer rescue mode boots from installation media and opens a shell in the installed root filesystem, even when the normal bootloader or startup sequence no longer works.
Rescue mode reuses the installer's language, keyboard, network, and disk detection screens. It then offers existing filesystems instead of starting partitioning or a new installation. The selected root filesystem becomes the shell's root, so its files and installed commands are available for repairs.
The installer image must match the machine's CPU architecture, and the machine needs local or remote console access. Encrypted storage also needs its unlock passphrase. The rescue shell runs as root and can change the installed system; backups remain necessary before repairs that could damage data.
Steps to boot Debian rescue mode from installer media:
- Attach Debian installer media to the machine.
A prepared installer USB stick or an attached installer ISO is suitable; a Debian Live image has a different boot menu.
- Boot the machine from the installer media using the firmware or hypervisor boot menu.
- Select Advanced options in the Debian installer boot menu.
The arrow keys move the selection, and Enter opens the highlighted entry.
- Select Rescue mode in the advanced menu.
The Install entries start a different operation; the rescue screens should show Rescue mode at the top.
- Select the language for the rescue environment.
- Select your location.
- Select the keyboard layout used by the console.
Keyboard layout matters when entering passwords or storage unlock passphrases.
- Accept a hostname for the rescue environment.
With working DHCP, network configuration completes automatically before this prompt. The default hostname is sufficient for local disk repairs. If automatic configuration fails, Do not configure the network at this time is suitable when the repair needs no network access.
- Continue with a blank domain name for local repairs.
- Select the time zone matching your location if prompted.
- Select the partition containing the installed Debian root filesystem.
The root device is /dev/vda1 here; its name will differ on other machines. Do not select an EFI system partition, a separate /boot partition, or a data partition as root. If storage is encrypted or uses LVM or RAID, additional unlock or activation prompts may appear before the root filesystem is available.
- Approve mounting a separate boot partition if it is healthy.
This prompt appears only when the installed system has a separate boot filesystem, such as /boot/efi. Mounting it makes it available for bootloader repairs; No avoids mounting a filesystem known to be damaged.
- Choose Execute a shell in <device> for the selected root filesystem.
If a damaged root filesystem prevents this shell from starting, Execute a shell in the installer environment provides a smaller set of tools. A successfully mounted installed root is available there under /target.
- Select Continue on the shell confirmation screen.
The message identifies the device that will be mounted as /. The resulting root shell has access to that installed system.
- Confirm the installed Debian release from the rescue shell.
# cat /etc/os-release PRETTY_NAME="Debian GNU/Linux 13 (trixie)" NAME="Debian GNU/Linux" VERSION_ID="13" VERSION="13 (trixie)" VERSION_CODENAME=trixie DEBIAN_VERSION_FULL=13.7 ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/"
The release should match the Debian installation selected for repair. The shell is now ready for commands against that system. When repairs are complete, exit leaves the shell; the installer media should be removed before booting from the installed disk again.