I have a Windows 10 disk from a computer, which I cloned. I plugged the disk into the USB port of the original computer, pressed F11 to get to the boot menu, selected the disk plugged into the USB port, and proceeded to boot. The result was the error message INACCESSIBLE BOOT DEVICE.


The disk works, of course, plugged into the SATA port. Plugged into other computers, booting up off the disk plugged into a USB port works.

I expect this behavior, as on a different computer Windows sees the configuration change (different motherboard, etc.), configures the new hardware configuration, and boots. When booting from the disk plugged into a USB port on the original computer, Windows fails to adequately detect the new configuration and yields the INACCESSIBLE BOOT DEVICE error.

I presume that I would need to change something in the registry to either force a new hardware configuration scan on boot or more preferably to made whatever changes are required in the registry that will tell Windows that the boot device is a USB drive now and not a SATA drive directly plugged into the motherboard.


  • This is a windows things... it blocks booting from removable disks. – Joel Coehoorn May 23 '18 at 18:39

There could be three different things going on here.

First of all, Windows normally blocks booting from removable disks. It won't boot from usb flash drives (or really any drive connected via USB). Sometimes you can trick Windows into starting up anyway, but it doesn't sound like you've tried that yet, and it's not easy to do. I couldn't find a good link that explains how.

IIRC (it's been a while!) this problem normally causes a different error message, so you may have something else going on as well... but when you solve that other issue (if any), you'll need to deal with this as well.

Second, Windows needs two partitions two boot. The first partition is small (100-500Mb) and only holds the boot manager. The boot manager has information about how to boot the actual operating system... including the disk and partition where the operating system are located. When you cloned the system to the USB drive, that reference changed. The low-level names for usb disks used by the Windows boot manager are different than those used for sata or ide disk, and thus the boot manager can't find your OS.

Finally, there could be a mismatch between an MBR and a GPT formatted disk. MBR disks are typically used with older style BIOS computers, and GPT disks are typically used with new UEFI systems... but you can find exceptions in both directions. It could be that trying to boot from the USB stick moved a GPT-partitioned hard drive onto an MBR-partitioned usb disk.

  • I should not have mentioned cloning, as that detracts from the question, however for posterity sake, the clone was to an identical SSD. Both are identical SATA 6Gb/s 250GB SSDs, Original disk to USB also has the same problem, so I made a mistake mentioning cloning. The duplicated disk is identical inclusive of the partitions. Your second point is more relevant. Thanks. – Sarah Weinberger May 23 '18 at 19:23
  • If you're connecting it to a usb port, it still counts as a removable disk and the Windows boot manager will refuse to use it. I do a lot of cloning via CloneZilla (just finished setting up a new Win10-1803 image this week), but I'd never expect my images to work via a usb port. – Joel Coehoorn May 23 '18 at 19:26
  • Not true, it boots nicely on any computer but the original. If you start off as a USB then Windows installs and boots forevermore as a USB. – Sarah Weinberger May 23 '18 at 19:30
  • If and only if you're running Windows Enterprise and have "Windows To Go" turned on. – Joel Coehoorn May 23 '18 at 19:34

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