How to repair System Docker on Proxmox?

I installed a special version of RancherOS v1.5.6 for Proxmox on Proxmox VE 5.3-6. I backup the VM and transfer it to Proxmox VE 6.4-4. On booting it up, I got the following error:

Loading ../vmlinuz-4.14-138-rancher...ok
Loading ../initrd-v1.5.6...ok

XZ-compressed data is corrupt

 -- System halted

I tried to boot up the system using this external disk image: rancheros-autoformat.iso

And it works just fine, so I can conclude that System Docker is the source of the problem. My question now is how do I repair it. I followed a set of instructions to install it on system disk initially, but if I were to install it over the current one, won’t all current settings be lost?

It seems something has changed when backing up and restoring since the checksum of the disk before and after is different. Since everything seems to work fine for the past weeks, I guess I don’t need to install it to the system disk after all. I can run it directly from the boot disk.