I'm trying to install Windows 10 in a virtual machine on Bazzite using the Flatpak version of Virtual Machine Manager and QEMU. When I try to redirect a USB device to the VM so I can access installation files, Virtual Machine Manager reports "Insufficient Permission [-3] (0)." My main account has administrator privileges, but I'm unsure whether the Flatpak sandbox or missing libvirt setup is causing the problem. What permissions or configuration changes are needed to make USB redirection work?
3 Answers
Adding your user to the libvirt group may be necessary, but it is not the same as granting the Flatpak access to USB hardware. After changing group membership, log out and back in—or reboot—so it takes effect. If the Flatpak continues to block USB passthrough even with the appropriate device permission enabled, using the distribution’s native Virtual Machine Manager package may avoid some of the sandbox limitations.
The Flatpak sandbox is the first thing to check. Open Flatseal, select Virtual Machine Manager, and grant access to USB devices—typically the Devices permission, such as “All devices.” Also make sure the app can access the libvirt connection it is using. Restart Virtual Machine Manager after changing permissions. Being an administrator does not automatically bypass Flatpak sandbox restrictions.
Make sure the VM is connected to the correct libvirt session and that the USB device is not currently being used by the host. The error is more likely an access restriction than proof that libvirt is missing. Check the app’s Flatpak permissions first, then verify the libvirt service and group membership.

Which specific permission should I enable? I tried changing several Flatseal options, but USB redirection still reports insufficient permission.