Win11Pro changes UEFI boot order -- on its own

Mark Phelps · Dec 8, 2023

UPDATE: After being gone for a long time, the issue has returned -- but with some changes.

First, I have figured out HOW to press the function keys to get the UEFI menu and/or boot order to appear -- that is a big PLUS to working around the issue.

Second, I did a clean-install of Win11 recently and now, the UEFI entry is different than before -- but it still works.

Third, when this happens, I have been in Win11 Pro, confirmed the boot order default before exiting, do a restart, and then am booted directly into Win10. I go into the UEFI settings and see that the boot order has been changed to put Win10 first in the list. If I restart from Win10, I get a BSOD!! So, I do a reboot, press Del to get into the UEFI settings and note that a non-OS volume is now first in the list. I change that to rEFInd and when I restart again, the menu comes up.

But the next time I restart from inside Win11 (which is needed for some app updates), I am automatically rebooted into Win10 -- again.

What is working now, is pressing the Del key when the boot screen comes up. That lets me select the boot drive I want -- so it is a way to work around this issue.

trumpy81 · Dec 10, 2023

When you boot from more than one OS, the Windows Boot Manager will reassign the selected drive and name it C:\ regardless of what the actual drive letter was.

In my case, I have 2 OS installed in a dual boot. The first drive created was C:\ (Win11) of course, and the second drive created was assigned Q:\ (Win10).

If I boot into Win10, then Q:\ becomes C:\ and C:\ becomes Q:\.

Win10 Selected at boot:
C:\ = Windows 10 installation drive
Q:\ = Windows 11 installation drive

Win11 Selected at boot:
C:\ = Windows 11 installation drive
Q:\ = Windows 10 installation drive

With 5 drives assigned as C:\, D:\, E:\ F:\, G:\

OS on D:\ selected at Boot:
C:\ = D drive
D:\ = C drive
E:\ = E drive
F:\ = F drive
G:\ = G drive

OS on F:\ selected at boot:
C:\ = F drive
D:\ = D drive
E:\ = E drive
F:\ = C drive
G:\ = G drive

This is normal behaviour for Windows when booting from multiple drives/OS.

SIW2 · Dec 10, 2023

Drive letters were probably not a good idea because they seem to confuse so many

trumpy81 · Dec 10, 2023

@SIW2
I agree, it also makes identifying the physical drives somewhat of a nightmare also, when you have multiple physical drives.

But, that's how Microsoft elected to handle things ...

SIW2 · Dec 10, 2023

the Windows Boot Manager will reassign the selected drive and name it C:\

You are mistaken but it is understandable why

If you look in the mounted devices key you will find letters which represent the very long number for the disk and partition.

Because that long number is hard for humans to use.

During the standard installation process windows assigns a letter to the partition it is on. By default that is C. It probably came about because in the olden days A and B were reserved for floppies, so the next available letter is C.

Sometimes a partition will not have a letter and the long numbers can also be represented to the user by a device path .

e.g. bcdedit will show your recovery partition as something like \Device\HarddiskVolume5

NavyLCDR · Dec 10, 2023

SIW2 said:
You are mistaken but it is understandable why

Correct. It is the Windows OS that assigns drive letters as the OS is loading, not the boot manager.

SIW2 · Dec 10, 2023

It is a common misconception that the os is always assigned letter C. There are some cicumstances in which the os has a different letter. It doesnt matter, the other letter functions just as well as an alias for the long numbers.

trumpy81 · Dec 10, 2023

The first link in the chain is the Windows Boot Manager. It signals Windows as to which drive etc. is selected, Windows then makes the necessary changes.

No Windows Boot Manager = no drive selected = Windows selects the default drive.

My wording was a little ambiguous, but I was not trying to explain the overall operations, just trying to make things digestible.

I hope that is clear enough for you?

ThrashZone · Dec 10, 2023

Hi,
Secure boot off and maybe sata priority or disk priority is off meaning disk 0 is not the os disk.

Post a free minitool or disk management screen shot.

ThrashZone · Dec 10, 2023

SIW2 said:
It is a common misconception that the os is always assigned letter C. There are some cicumstances in which the os has a different letter. It doesnt matter, the other letter functions just as well as an alias for the long numbers.

Yeah it's only C when you boot into it lol

NavyLCDR · Dec 10, 2023

ThrashZone said:
Yeah it's only C when you boot into it lol

Not always.

ThrashZone · Dec 10, 2023

NavyLCDR said:
Not always.

Hi,
Is that the failure to boot error time :think:

ThrashZone · Dec 10, 2023

Hi,
Here's my z490 win-11 atm mbr of course but still secure boot is off.
This is what I was referring to it really helps my boot accuracy if disk 1 is os
If I swapped m.2 slots 50-50% chance it would boot to the data m.2.

ThrashZone · Dec 10, 2023

Noticed my new acer lappy os is in disk 2 slot only reason it has no boot issues is secure boot.

trumpy81 · Dec 10, 2023

If I swapped m.2 slots 50-50% chance it would boot to the data m.2.

No it would not, you cannot boot from a data disk ... lol

It does not matter what drive number is assigned in the BIOS, you must manually select which drive to boot from in BIOS. If you don't select the correct drive, the system will not boot, period.

ThrashZone · Dec 10, 2023

Exactly you get boot error lol

trumpy81 · Dec 10, 2023

Uhuh ... lol

NavyLCDR · Dec 10, 2023

ThrashZone said:
Hi,
Is that the failure to boot error time

Nope. Nothing on this computer but D: drive.

Code:

Microsoft Windows [Version 10.0.19045.2965]
(c) Microsoft Corporation. All rights reserved.

D:\Windows\system32>bcdedit

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
default                 {current}
resumeobject            {3cbfc693-8bc7-11ee-b2b0-84e9f6fdd286}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=D:
path                    \Windows\system32\winload.efi
description             Windows 10
locale                  en-US
inherit                 {bootloadersettings}
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=D:
systemroot              \Windows
resumeobject            {3cbfc693-8bc7-11ee-b2b0-84e9f6fdd286}
nx                      OptIn
bootmenupolicy          Standard

D:\Windows\system32>diskpart

Microsoft DiskPart version 10.0.19041.964

Copyright (C) Microsoft Corporation.
On computer: DESKTOP-7QCJHAV

DISKPART> lis vol

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     D   WIN11        NTFS   Partition    126 GB  Healthy    Boot
  Volume 1                      FAT32  Partition    100 MB  Healthy    System

DISKPART>

dacrone · Dec 10, 2023

Make a hirens boot usb. Boot it and use the bcd tool. See how many x64 boot files are there. I’ve seen it have 2 and it gets confused. Not sure, but worth a try here.

trumpy81 · Dec 10, 2023

@NavyLCDR
So why do you have Windows 10 File Explorer and Disk Management showing if you are running Windows 11?

Have you used some mods?

Which mods?