A little update: I found out that I have to activate *Hostdev Passthrough* (is this really necessary for USB devices?). Now I see all the devices and I can add also an USB device. But I'm still not able to disconnect the USB from the old VM. ---------- Forwarded message ---------- From: Jon bae <jonbae77(a)gmail.com&gt; Date: 2018-02-12 16:14 GMT+01:00 Subject: Can't add/remove usb device to VM To: users <users(a)ovirt.org&gt; Hello, I run oVirt 4.2.1, in 4.1 I added a USB device to a VM and now I wanted to change this device to a different VM. But I found out, that I'm not able to remove this device nor I'm able to add any device to any VM. The device list is empty. I found a bug report, what describe this error: https://bugzilla.redhat.com/show_bug.cgi?id=1531847 Is there a solution for that? The USB device is a hardware dongle and it is very impotent for us to change this. Any workaround is welcome! Regards Jonathan