How to Use Recovery Mode on Ubuntu to Troubleshoot Startup Issues

Ubuntu recovery mode is a troubleshooting menu launched from GRUB. It starts Ubuntu with a limited set of services and offers tools for freeing disk space, repairing package work, checking filesystems, refreshing GRUB, or opening a root shell. To enter it, restart the computer, open GRUB, select Advanced options for Ubuntu, then choose a kernel entry ending in (recovery mode).

Recovery mode is useful when a normal startup fails, but it is not a backup or a full live environment. Menu labels can vary by Ubuntu release and installation. If the disk makes unusual noises or disappears intermittently, prioritize copying important files from a live USB or getting help before running repairs that write to the disk.

Boot into Ubuntu recovery mode

1. Restart the computer. Use the desktop’s restart command if Ubuntu still runs. If it does not, power the machine off normally if possible, then turn it on again.
2. Bring up GRUB. On many UEFI systems, tap Esc after the firmware screen appears. On legacy BIOS systems, hold Shift during startup. The timing varies, and some computers use a firmware boot-menu key. If Ubuntu starts before GRUB appears, restart and try again.
3. Open the advanced entries. In the GRUB menu, use the arrow keys to highlight Advanced options for Ubuntu and press Enter.

4. Choose recovery mode. Select the Ubuntu kernel entry ending in (recovery mode) and press Enter. If the problem began after a kernel update, an older kernel entry can also help identify whether the new kernel is involved. If Ubuntu uses full-disk encryption, enter the disk passphrase when prompted.

After startup, the Recovery Menu appears. Use the arrow keys and Enter to choose an item. Select one action that matches the problem; running every option is unnecessary. The Ubuntu recovery-mode guide documents the GRUB path and the root shell’s read-only starting state.

What the recovery menu options do

Network: connect before package downloads

Choose network when a package repair needs to retrieve files from Ubuntu repositories. A wired connection is often the simplest option in recovery mode. Networking may not work with every wireless adapter or managed network; if the repair cannot reach a repository, note the error and use a live environment or another support path.

Clean: address low disk space

clean attempts to free space, which can help when an update or startup failed because a system partition filled up. Read the on-screen summary before confirming any action. It is not a file-recovery tool and will not restore personal documents.

Dpkg: repair package-manager problems

dpkg checks for and attempts to repair broken or incomplete package installation state. Review the proposed changes before accepting them; a repair may install, configure, or remove packages. It can need a working network connection if required packages are missing. Ubuntu’s dpkg manual and APT manual explain the underlying package tools.

Fsck: check filesystem consistency

fsck runs filesystem checks and may offer repairs. This is different from scanning a drive for bad hardware, and it cannot guarantee that damaged files will be restored. Let the recovery menu handle the check. Do not run a filesystem checker manually on a filesystem that is mounted read/write; the Ubuntu fsck manual warns against checking mounted filesystems. If the check reports errors it cannot repair, stop and back up data before attempting more changes.

Grub: refresh the boot menu

grub refreshes GRUB’s configuration and can help when menu entries are stale or missing. It does not necessarily reinstall a missing bootloader or fix every UEFI boot problem. If GRUB itself cannot start, use Ubuntu installation media and follow a bootloader-specific recovery procedure instead of guessing at disk or EFI partition commands.

Root: use the administrator shell carefully

root opens a command line with administrator privileges. Ubuntu normally mounts the root filesystem read-only in this shell. If you have identified a specific file to edit, the official recovery guide documents remounting it read/write with:

mount -o remount,rw /

Run only commands you understand, because root commands can change or delete system files. If the command fails or the filesystem reports I/O errors, do not force a repair. Choose resume to try a normal boot after a repair, or restart from the shell when appropriate. Recovery mode provides powerful local access, so do not leave the computer unattended at a root prompt.

If recovery mode does not appear

If GRUB is hidden, try the startup keys again or use the computer’s one-time boot menu. If the machine uses another boot manager, the Ubuntu recovery entry may not be available there; boot the Ubuntu installation USB and use its live session to inspect the system. Avoid running fsck against a mounted root partition. For persistent boot failures, save the exact error text and check the disk health before repeating repairs.

Official references

• Ubuntu Wiki: Recovery mode
• Ubuntu Community Help: filesystem troubleshooting
• Ubuntu Manpages: fsck
• Ubuntu Manpages: dpkg
• Ubuntu Manpages: apt-get