I agree with @addyp95 - this is a bug in how libvirt works in IPv6-only environments, and it is still present on focal. For posterity, the exact details of the workaround are to add the following line to /etc/libvirt/qemu.conf:
spice_listen = "::1" ** Changed in: qemu (Ubuntu) Status: Invalid => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1492621 Title: Cannot start VMs without routable IPv4 address To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1492621/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs