Xen: libvirt.libvirtError: An error occurred, but the cause is unknown

Hi, I'm facing a strange issue with libvirt and the Xen driver. Whenever I try to define or start a domain, I always get this error: "libvirt.libvirtError: An error occurred, but the cause is unknown" (in Python virt-manager interface) Which is not very helpful. Trying to use virsh directly leads to the same error message: virsh # start win10_xen error: Failed to start domain win10_xen error: An error occurred, but the cause is unknown I checked /var/log/libvirt/libxl/libxl-driver.log, but the log file is empty. However, using the xl toolstack directly to start a new domain works fine, so the issue doesn't seem to come from Xen. My environment: - Ubuntu 20.04 LTS - xen-hypervisor-4.11-amd64 (4.11.3+24-g14b62ab3e5-1ubuntu2) - libvirt0 (6.0.0-0ubuntu8.8) I really like libvirt and virt-manager to manage my VMs. Any clue how I could dig deeper and find the root cause ? Thanks.