R4.3 Error: "qubes-usb-proxy" is not installed, when it is actually installed

User Support General
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Hello and happy new year. This is my first post on this forum and I hope that I didn’t miss anything. I went from my issue and researching online straight to creating my account and posting here.

I am running Qubes R4.3 fresh install. This issue did NOT exist in Qubes R4.2.4 on the same machine.

Does the community know of this problem? Is there a known solution/workaround to this? I will consider filing a bug report on GitHub if not.

My issue: I encounter an issue that qubes-usb-proxy is not installed when I try to attach a YubiKey to a Qube, where it is supposed to be used with KeePassXC, despite qubes-usb-proxy definitely being installed.

My configuration:

  • Lenovo ThinkPad T460s, running Qubes R4.3 on bare-metal. USB keyboards and mice work and are detected regularly with this configuration.
  • Two (relevant) templates, based on fedora-42-minimal.
  • One template is used for system qubes, including for the disposable sys-usb HVM qube handling USB devices.
    The disposable template for sys-usb is custom-created and points towards the system qube template. No configuration was done on this template.
    All necessary packages as per the Minimal Template documentation are installed, including qubes-usb-proxy and qubes-input-proxy-sender. qubes-ctap is also installed but this should not matter here.
  • Another minimal template is used for a snap-installed KeePassXC. Only packages relevant to KeePassXC and snapd functionality are installed, as well as qubes-usb-proxy.

When I attach a YubiKey to the laptop and then select the qube used for KeePass, I get an error that qubes-usb-proxy is not installed. I get this error as well when I attempt to use qvm-usb attach <name-of-qube> sys-usb:<port>.
Changing the port doesn’t matter. It doesn’t matter if I reinstall qubes-usb-proxy on both templates and then reboot sys-usb and the KeePass qube. It doesn’t matter if I allow the YubiKey to be attached to dom0 beforehand or not.

Again, with a similar configuration, this error did not occur in R4.2.4 and the YubiKey attached itself without problems.

Any help with this would be much appreciated!
-Von