6.4 to 7.2

Hi, I am planning to upgrade 2 live installations of Proxmox 6.4 to 7.2 but before I do, I have setup a local machine, clean install the 6.4 iso and I am having problems to upgrade it to 7.2. If i can't do that successfully here, I won't be able to do it on the live servers. I am running and I...