Comment 5 for bug 1931716

TBH "operation failed: disk vdb not found: libvirt.libvirtError: operation failed: disk vdb not found" sounds like one of the old error codes that we removed in the recent-ish past. Old code [1]:

    except libvirt.libvirtError as ex:
        with excutils.save_and_reraise_exception(reraise=False) as ctx:
            errcode = ex.get_error_code()
            # TODO(lyarwood): Remove libvirt.VIR_ERR_OPERATION_FAILED
            # and libvirt.VIR_ERR_INTERNAL_ERROR once
            # MIN_LIBVIRT_VERSION is >= 4.1.0
            if supports_device_missing_error_code:
                unplug_libvirt_error_codes.add(
                    libvirt.VIR_ERR_DEVICE_MISSING)
            if errcode in unplug_libvirt_error_codes:
                # TODO(lyarwood): Remove the following error message
                # check once we only care about VIR_ERR_DEVICE_MISSING
                errmsg = ex.get_error_message()
                if 'not found' in errmsg:
                    # This will be raised if the live domain
                    # detach fails because the device is not found
                    raise exception.DeviceNotFound(
                        device=alternative_device_name)

[1] https://github.com/openstack/nova/blob/dd1e6d4b0cee465fd89744e306fcd25228b3f7cc/nova/virt/libvirt/guest.py#L417-L427