Sunday, October 13, 2024

PC suddenly or inexplicably won't recognize UEFI boot device(s)

Problem:  As title.  May show up on a machine that has been booting from USB for years.  USB media is working; no settings in BIOS help; moving the USB boot device to other USB ports doesn't help; rebuilding USB media doesn't help. 

A:  You might have plugged in a new USB hub, or other device, that is stopping your mainboard from finding the USB boot device.

I had this happen when I upgraded a little D-Link hub on my desk to a larger model with more ports.  Everything was fine in Windows, but on boot, this hub prevented my mainboard from detecting my USB boot drive.

It is indeed the hub, and not anything plugged into the hub.  I tried.

As a BIOS is relatively simple, I'm guessing the new hub (which is USB 3.0) is somehow incompatible with the BIOS detection protocol used to find UEFI boot devices.

As my mainboard is hardly current, this could be limited to just this hub, or maybe to all USB 3.0 hubs connected to older mainboards that don't support newer protocols.

I only use the USB drive to boot into a backup/recovery environment, so it wasn't a major thing.  But as a back up weekly, it is annoying, as I have to disconnect the new 3.0 hub in order to boot to backup mode.  I'll be trying another model.

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