If the backup you have is unavailable/not working, then you can either get the original file from this repo directory (if you have one of those 3 supported versions) or you can update your PVE install to the latest version by following this - https://pve.proxmox.com/wiki/Downloads#Update_a_running_Proxmox_Virtual_Environment_6.x_to_latest_6.2.
Updating will replace the files (apart from charts.js - whose original you can grab from any PVE version folder from here since its not changed).
