Chapter 8. Next Steps and Where to Go From Here 8.7. Recovering a Broken System Then press either Ctrl-x or F10 to boot with the modified entry and the system will enter the rescue mode. Sometimes, things go wrong, and the system you’ve carefully installed is no longer bootable. Perhaps the boot loader configuration broke while trying out a change, or perhaps a new kernel you installed won’t boot, or perhaps cosmic rays hit your disk and flipped a bit in /sbin/init . Regardless of the cause, you’ll need to have a system to work from while you fix it, and rescue mode can be useful for this. There are several options to rescue a broken Ubuntu system on arm64: While booting the system enter the boot loader menu: Then type e to edit the boot loader configuration and entries, navigate to your prefered Linux kernel line and append either rescue or systemd.unit=emergency.target . • To access rescue mode, select rescue from the boot menu (if available) or append the boot param- eter rescue or systemd.unit=emergency.target to the linux kernel boot entry of the boot loader. GNU GRUB version 2.02 GNU GRUB version 2.02 Use the ↑ and ↓ keys to select which entry is highlighted. Press enter to boot the selected OS, ’e’ to edit the commands before booting or ’c’ for a command-line. * Ubuntu Advanced options for Ubuntu insmod ext2 set root=’hd0,gpt2’or Ubuntu if [ x$feature_platform_search_hint = xy ]; then search --no-floppy --fs-uuid --set=root --hint-bios=hd0,g\ pt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 ea967ae0-7519-11eB-85b\ d-5254008bdef4 else search --no-floppy --fs-uuid --set=root ea967ae0-7519-11e\ 8-85bd-5254008bdef4 fi echo ’Loading Linux 4.15.0-23-generic ...’ linux /boot/vmlinuz-4.15.0-23-generic root=UUID=ea96\ 7ae0-7519-11eB-85bd-5254008bdef4 ro maybe-ubiquity rescue Minimum Emacs-like screen editing is supported. TAB lists completions. Press Ctrl-x or F10 to boot, Ctrl-c or F2 for a command-line or ESC to discard edits and return to the GRUB menu. ... [ OK ] Started Update UTMP about System Runlevel Changes. You are in rescue mode. After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or "exit" 80