System Manager - Change root password on VM Instances

Reactivate Account and Modify Kernel option in GRUB:

    Reboot the vCenter Server appliance using the vSphere Client.
    When the GRUB bootloader appears, press the spacebar to disable autoboot.

    Note: After powering on, the virtual machines takes only a short time to exits the BIOS/EFI and to launch the guest operating system. You can adjust the boot delay or force the virtual machine to enter BIOS or EFI setup screen after power on. For more information, see the Delay the Boot Sequence in the vSphere Client section in the VMware vSphere 5.5 Single Host Management Guide.
     
    Type p to access the appliance boot options.
    Enter the GRUB password.

    Note:
        If the vCenter Server appliance is deployed without editing the root password in the Virtual Appliance Management Interface (VAMI), the default GRUB password is vmware.
        If the vCenter Server appliance root password is reset using the VAMI, the GRUB password is the password last set in the VAMI for the root account.
    Use the arrow keys to highlight VMware vCenter Server Appliance and type e to edit the boot commands.

    Modifying the GRUB boot loader to start root password reset process
    Scroll to the second line displaying the kernel boot parameters.

    Scroll to the second line displaying the kernel boot parameters
    Type e to edit the boot command.
    Append init=/bin/bash to the kernel boot options.

    Append init=/bin/bash to the kernel boot options
    Press Enter. The GRUB menu reappears.
    Type b to start the boot process. The system boots to a shell.
    Reset the root password by running the passwd root command.
    Restart the appliance by running reboot command.

 

If error received " Authentication manipulation error"  mount / with rw permissions

mount -o remount,rw /

run passwd again and change password

    Note: If you cannot restart the appliance by running reboot command, then run these commands:

    mkfifo /dev/initctl
    reboot -f

 

    In order to prevent this issue from happening again in the future, you could set the root password to never expire at the VAMI page or by running this command: chage -I -1 -m 0 -M 99999 -E -1 root
    Verify the root account password expiry settings have been changed using the following command:  chage -l root