TeraByte Unlimited

I have come across very strange problem on one my desktop with BootIt UEFI when certain actions with this software can cause Windows 10 boot to fail with INACCESSIBLE_BOOT_DEVICE message. This desktop (Asus x99 Deluxe) has two disk drives. Drive #1 (Intel 905p NVMe SSD) is bootable GPT drive with EFI partition, Windows partition, Recovery partition and data partition (with image files made by Image for UEFI). Drive #2 (HDD) is GPT drive with two data partitions where second smaller partition has exactly the same size as data partition on drive #1. Making partition image files (full backup) and restoring them with Image for UEFI works without issues, but copy partition from one drive to another (small data partition in this case) while completes successfully cause Windows 10 boot to fail with INACCESSIBLE_BOOT_DEVICE message. Fast startup and hibernation are disabled.

After two failed boot attempts Windows goes to repair mode: Preparing Automatic Repair -> Choose your keyboard layout. On next screen I choose “Exit and continue to Windows 10” and Windows boots normally. If after that I reboot Windows, boot to BootIt UEFI and with Image for UEFI restore EFI partition, Windows partition and Recovery partition to state right before I did copy partition, Windows boots normally. So looks like Windows “repair” changes nothing on disk (NVRAM variables maybe?). If copy partition is done by BootIt UEFI Partition Works, it does not affect Windows boot. It does not matter if BootIt UEFI boots from CD/USB or it is it is installed on disk drive (EFI partition). Actually, if BootIt UEFI is installed on disk drive it always boots successfully.

There are no issues on my second desktop (Asus Z170 Deluxe) with identical drives, so it may be related to some specifics of UEFI on X99 motherboard. While I have a workaround by using BootIt UEFI Partition Works for copy partitions, the problem is very annoying.

RoundRobin,

When you do the copy in IFU have you been using the "Change GUID" option?

No, I have not been using it.

Try it. The system might not like two OS with the same GUID.

I just tried it without Change GUID and got your error.

I tried "Change GUID" option and it worked. Thank you! But I still have couple questions:

Why copy data partition (not OS partition) without "Change GUID" options has no issues on one system and cause Windows boot to fail on another, if Windows OS and drive/partitions setup is identical?

How important in general to change GUID while coping data partition from one drive to another even if this partition is “hidden” from Window (no letter is assigned to it)?

I meant to say "two partitions with the same GUID". It shouldn't matter if both are hidden from the OS, the OS will see the identical GUIDs.

I tried copying a data partition from one drive to another (IFU) without Change GUID and the OS didn't boot.

INACCESSIBLE_BOOT_DEVICE (0x7b) means Windows couldn't find or access the
boot partition (which it calls the system partition) completeness, it also
can occur in low memory situations and if gaps (empty entries) in the gpt exist
prior to windows partitions required to boot. But in general, in most cases it
comes from missing storage drive or file system dirty and needs chkdsk /r on it.

If you copy a data only partition it wouldn't affect booting, even if there
was a guid collision, it shouldn't affect it. The BCD not finding the
partition would give a different type of error, so the hand off to windows
already occurred, from there something prevented windows from finding the
boot partition.

You say it always boots okay using BIU, but it shouldn't matter unless
hiding items.

I repeated my test...

A 5 GB NTFS partition was created on HD5 (the ESP, OS drive)
The partition was copied to HD4 with IFU and Change GUID wasn't selected
In the Win10 Boot Item both NTFS partitions were set to Hide

I clicked Boot for the Win10 boot item. I saw the rotating dots for about a minute and then a very brief BSOD (too brief to read). The computer restarted into the BIOS. With BIOS beeps.

The computer was restarted and the same things happened.

The computer was restarted and Win10 went into Automatic Repair. I aborted this and booted BIU and deleted the NTFS partition on HD4.

Win10 booted normally. That is weird.