So I just did a test install of gnome-boxes using MX Package Installer, it installs and opens fine, but the window you shared a screenshot of manifested when I tried to create a Fedora VM quick.
I get the same line you had in your log
Code: Select all
(gnome-boxes:5119): Boxes-WARNING **: 13:57:33.262: review-page.vala:32: Box setup failed: Failed to create volume: internal error: creation of non-raw file images is not supported without qemu-img.