Troubleshooting dual boot W10-W11

It appears I need some help troubleshooting my dual boot setup. Previously I always avoided such problems by always having one hard drive with one OS (turning off other hard drives with other OSes so that they would not interfere). Now I could not avoid it since my Windows 10 sits on a NVMe drive that I cannot simply turn off.

So, when I installed Windows 11, I used an empty drive, but this wasn't the only drive in the system, the NVMe drive was also present. Now, the way I installed Windows 11: I first installed the most Windows 10 dev channel build and then updated it to Windows 11.

After the Windows 10 dev build was installed, the dual boot screen would appear with two Windows 10 installations and I did check that I could boot to both of them without any problems. Afterwards, the dev build got updated to Windows 11 and I installed some drivers (SATA, chipset, etc.). Now when I wanted to boot to my main Windows 10 I suddenly had a problem - I got a blue screen with a QR code stating that the boot media is missing. The machine then rebooted, attempted automatic repair, no joy. I turned off the Windows 11 drive, same issue. Now after the system informed me that the automatic repair has failed I clicked on Advanced options, eventually managed to boot to the safe mode, run sfc /scannow, it finished stating that some files were found corrupt and were successfully repaired. Now I can use my Windows 10 again.

However, before I go back to playing with Windows 11, I'd like to troubleshoot the issue and I am a bit at a loss. How can I find out what went wrong?

If it is any help, here;s the bcdedit output:

Looking forward to seeing if anyone has any insights on this. I had multiple issues dual booting 8 and insider 10 when 10 was first released. I was just getting ready to install 11 on a clean drive to try dual booting, I think I may wait. Looking at the bcd info I see in the first boot loader section that both device, and osdevice are showing unknown.

Gramps said:

Looking at the bcd info I see in the first boot loader section that both device, and osdevice are showing unknown.

Click to expand...

That's because the drive with Windows 11 is turned off at the moment.

That is odd. I multiboot all the time . Currently have win7, vista , win11 all on different drives on the same mbr disk. Working fine.

The gpt disk is a bit fiddly. It has vista, win7 and win11 all on the same drive. So I move the namespace folders depending which os I want to boot into.

It seems the win11 efi boot critical files dont like to boot Vista, so I have to swap them to boot vista in efi mode .

Looking for hints of what happened I found this



with all three critical events having similar technical details



The difference is in the long hexadecimal file name.

I suppose the sfc /scnnow command replaced these files and everything runs. However, I have no idea what these files are and how did they get "corrupted". What exactly is "corrupted"?

Your set up is similar to mine.
I have my original Win10 Pro dual booting with Win 11 Pro.
Win 10 is on an NVME M.2 and Win 11 Pro was installed on a spare SSD
Dual booting works without any problems (so far!).
Comparing your BCEDIT output with mine shows that your WIn 11 installation is showing "unknown" as the location of the device and osdevice. Mine shows "partition c:" for both these fields.

Perhaps EasyBCD utilities can sort this out for you. https://neosmart.net/EasyBCD/

Is the other disk attached

Yes it is. Currently running Win 11 on the SSD.

You could do

bcdedit /set {GUID} device partition=s:
bcdedit /set {GUID} osdevice partition=s:
to change the description of one of those entries
bcdedit /set {GUID} description "Win 11"

use the identifier guid from your bcdedit output and replace s with whatever partition you want to point at.

In my case the other disk was turned off.

Make sure to run:
on all Windows installations set up for dual booting. Hibernation and Windows Fast Startup will interfere with dual booting. The above command disables both.

I have hibernation turned off in Windows 10, but I did not do anything about that in Windows 11. Still, the dual boot works, once I have restored the Windows 10. I am tending to conclude that SATA driver was the culprit that messed up the original Windows 10 install.

It is not really recommended to install or update a second OS with another hard drive installed. Specially if it is another OS drive. The installation/update process can detect the wrong drive to install the boot drive. But this is usually hit or miss.
But if you have backup image, it will be less of a worry because if things like this happen, you can just do an image restore of the messed up OS.

badrobot said:

It is not really recommended to install or update a second OS with another hard drive installed. Specially if it is another OS drive. The installation/update process can detect the wrong drive to install the boot drive. But this is usually hit or miss.
But if you have backup image, it will be less of a worry because if things like this happen, you can just do an image restore of the messed up OS.

Click to expand...

This typically true, although I would characterize this as a workaround, rather than a solution, especially since there is no easy way to turn off a NVMe drive. It should not be expected of one to open up the box, physically remove a drive, install the OS on another drive, then reassemble the computer. Moreover, it's unclear how it will behave afterwards - which bootloader will be used. With SATA drives, I have a hardware switch that can turn drives on and off. When booting an OS, I can turn off drives with other OSs and then there is no conflict. But with the NVMe drive it is not possible at the moment. Hence, the bootloader has to reside on the NVMe drive. In my system that's the drive with Windows 10 (my main "production" system). The drive with Windows 11 is SATA and hence can be turned off when I'm using Windows 10.

Now, as you can see from this thread, it was not the installation if Windows 11 that messed things up, but rather the install of the Intel SATA driver thereafter.

And yet that is exactly what people have been forced to do with NVMe drives at one point or another, don't remember if it was with a particular chipset, particular mobo manufacturer, particular implementation of NVMe, or even MBR vs GPT (but it was mentioned in another thread.

oh, and SATA drives. And populating multiple DIMM slots (notably, but not limited to, the X58 boards and CPUs that supported triple channel memory).... and many other cases as well.