Resetting the root account password on the PVE Host

The following follows the general method for resetting a root password on a Linux machine, if you have access to the console see e.g.:

for similar suggestions.

Keep in mind that editing the kernel command-line might need a different key-entry based on your boot-loader (e works for both grub and systemd-boot though). The method works for Proxmox VE until version 8.1 and should work for many other Linux based Operating systems as well:

Method 1

Boot into your bootloader (mostly grub or systemd-boot, select your preferred kernel but do not press enter.
Press e to go into edit mode.
Depending on the boot-loader go to the kernel-commandline entry:
- For grub: scroll down to the kernel line you will boot from, it starts with linux /vmlinuz-...
- For systemd-boot the kernel commandline is directly editable
Scroll to the end of that line, optionally remove the quiet in the line and append init=/bin/bash
For grub press Ctrl X to boot, for systemd-boot simply press Enter

In the resulting shell:

# Remount / as Read/Write 
mount -o remount,rw /

# Change the root account password with
passwd

# Change any other account password with
passwd username

# type new password, confirm and hit enter and then reboot.

Method 2

Boot from a Live CD, which supports the / filesystem of your PVE installation (mostly relevant for installs on ZFS) (e.g. a Proxmox install ISO, in debug-mode (second debug-shell))
Mount the / filesystem in read-write mode at a free directory (e.g./mnt will be used in this example).
- you might need to do other steps, based on the filesystem, e.g. zpool import -f -R /mnt rpool for ZFS.
Run passwd -R /mnt to set a new password for the root account.
Unmount/export the /-filesystem and reboot.

Resetting the root account password in a Container

Enter the working container and change the password using:

pct enter <VMID>
passwd
# enter new password in silent prompt
exit

If you're still using OpenVZ containers, which are not supported in Proxmox VE 4 or newer, you can use vzctl enter <VEID> to enter the container.

Resetting the root account password on the PVE Host

Method 1

Method 2

Resetting the root account password in a Container

References