How to fix Error:VM is locked (backup) on Proxmox VE

I was unable to start my virtual machine on Proxmox VE Server and I got the following error shown on the web interface everytime I tries to start the VM.

Error: VM is locked (backup)

After googling, I found the solution for this error:

Log in to the Proxmox VE server and execute the following command as root.

qm unlock 100

Change 100 with the VM ID you want to unlock.

Output:

root@cluster1:~# qm unlock 100
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LC_PAPER = “id_ID.UTF-8”,
LC_ADDRESS = “id_ID.UTF-8”,
LC_MONETARY = “id_ID.UTF-8”,
LC_NUMERIC = “id_ID.UTF-8”,
LC_TELEPHONE = “id_ID.UTF-8”,
LC_IDENTIFICATION = “id_ID.UTF-8”,
LC_MEASUREMENT = “id_ID.UTF-8”,
LC_TIME = “id_ID.UTF-8”,
LC_NAME = “id_ID.UTF-8”,
LANG = “en_US.UTF-8”
are supported and installed on your system.
perl: warning: Falling back to a fallback locale (“en_US.UTF-8”).

Now I can start my VM without problem.