No /mnt/sysimage/boot/efi/EFI/qubes/xen.cfg file exist

[ChrisA]

Did you select the default kernel … or did you try with kernel latest when you installed Qubes OS?

either way - have you tried the steps at:

Nvidia Troubleshooting Guide

System freezes during boot / Graphical login manager is not visible If you have an NVidia graphics card it will probably not work under Xen out of the box. If your system freezes during boot and you don’t see the graphical login manager after you installed Xen, then this problem most likely affects you. The following steps should provide a workaround so that you should be able to use your NVidia with X under Xen, however without any fancy “desktop effects”. Boot in failsafe Boot your system u…

[notice: The link is to the section about GRUB - which is used by Qubes OS 4.2]?

Does it help to replace the quiet with:

nouveau.modeset=0 rd.driver.blacklist=nouveau video=vesa:off

?