Can't create a virtual machine: chardev 'spicevmc' not supported without spice graphics
When creating a new virtual machine, the creation process gets stuck on "Review and create" (only the loading spinner is shown, and nothing else). The following message is printed in the logs:
(gnome-boxes:28541): GLib-GObject-CRITICAL **: 18:44:51.913: g_object_get: assertion 'G_IS_OBJECT (object)' failed
(gnome-boxes:28541): Boxes-WARNING **: 18:44:55.208: review-page.vala:44: Box setup failed: Failed to create domain: unsupported configuration: chardev 'spicevmc' not supported without spice graphics
(gnome-boxes:28541): Boxes-CRITICAL **: 18:44:55.208: boxes_assistant_review_page_populate: assertion 'machine != NULL' failed
This seems to be an issue with some recent libvirt upgrade, since most search results for the "unsupported configuration" error seen above point towards Arch users having similar issues with virt-manager. The solution there is to modify the machine config (ref 1, ref 2, ref 3).
I'm experiencing this issue on Alpine Linux edge, with GNOME Boxes 42.0.1, qemu 7.0.0 and libvirt 8.5.0. There's also a report of a similar bug on Void Linux.