Sometimes it might be necessary to start in single-user mode to do some administration work, or even reset an existing password. Normally this can be achieved via the GRUB boot loader. CentOS / RedHat (with root account enabled) Switch on your system. Press Esc until the GRUB menu shows up.…
ZFS ‘Failed to start Mark current ZSYS boot as successful’ fix
On Ubuntu 20.04 after installing the NVIDIA driver 510 metapackage the system stopped booting. It will either hang with a black screen and blinking cursor on the top left or show the following error message: Attempting to revert from a snapshot ends up with the same error message. This wasn’t…
Ubuntu/GRUB: Error: invalid environment block
After a recent system update I got the following error message: Luckily the system would boot up but ignoring errors isn’t best practice. This error is caused by a faulty GRUB2 environment block. This is a file located in /boot/grub/grubenv. You can easily regenerate it with the following commands. It…
Ubuntu/Debian: Not enough free space on disk ‘/boot’ when updating the OS
My /boot partition is only 512MB and I get this error message every now and then when updating: Not enough free space The upgrade needs a total of xx.x M free space on disk ‘/boot’. Please free at least an additional xx.x M of disk space on ‘/boot’. You can…
Ubuntu: Fixing the “error: no video mode activated” message on boot
During boot of your system and just after the BIOS messages Ubuntu might display a black screen with an error: no video mode activated message. The system boots normally but it is annoying. GRUB by default hides the boot menu and this message can show up if there is no…
