Now I arrived at the same case you had - a slightly off-defaults guest that booted into the ISO again as we have configured it to do it that way. And now - while booted into the ISO you want to detach. Actually that won't work on a physical device either, the CD will refuse to eject as it is in use - something like that could happen here as well.
In both cases (Focal/Hirsute) at this stage it looks like this from the Host: <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source file='/var/lib/libvirt/images/CentOS-7-x86_64-Minimal-2009.iso' index='1'/> <backingStore/> <target dev='hda' bus='ide'/> <readonly/> <boot order='1'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> Detaching (=selecting to no more apply this iso as backing for the CDrom) this from the virt-manager UI interface gives works just fine. >From the Host it now looks like: <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source index='4'/> <backingStore/> <target dev='hda' bus='ide'/> <readonly/> <boot order='1'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> If I'd try to use it by now e.g. continue the installer the guest gets an I/O error on the cd, which is pretty much what you'd expect. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1930398 Title: libvirtd unable to execute QEMU command 'blockdev-remove-medium' To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1930398/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs