USB Passthrough issue during flashing in windows VM

venkat.akula

New Member
Aug 10, 2026
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I am using a Windows 10 VM on Proxmox for flashing a target. Two USB devices are passed through to the VM:
  • One is used for the COM/serial ports
  • The other is used for DFU flashing
During flashing, the DFU usb device is expected to disconnect and reconnect with another name. However, it looks like the device is not being properly detected after reconnecting. The DFU device shows up as unknown after reconnecting, causing the flashing process to fail.

Same results with passing through via port and PID:VID.

The same flashing setup works correctly on a physical Windows machine.

Has anyone experienced a similar issue with USB passthrough in Proxmox, or found a reliable way to handle this type of USB disconnect/reconnect?
 
PCI(e) passthrough of a whole USB controller typically prevents such issues, but that comes with a whole new set of caveats.
Yes, this worked. However, we are planning to run multiple VMs, with each VM needing its own USB devices for flashing. Passing through the entire USB controller would dedicate that controller to a single VM. Is there an alternative way to handle this?