@olivierlambert I did right now a fresh install of XCP-ng 8.2.1 in this server. Grub menu is this:
choosing the first item (default) I get this error(so it begins looping):image_2023-09-29_174135837.png
the second item (XCP-ng (Serial)) got a successfull boot.
Now I remember what I did... I tried to make XCP-ng (Serial) the default option but I ended corrupting grub... Tell me how I turn it the default option?