Windows 10: Dual Windows OS system cannot boot with only one OS

Hello all,I have 2 nvme SSDs on my system that each contains its own Windows installation, one with Windows 10, one with Windows 11.I bought the second SSD a few months back, installed Windows 11 on it, and it works like a charm. However, I am always prompted with the select an operating system whenever I boot up.Today, when I tried to remove the SSD with Windows 10 on it, my PC would boot straight to BIOS. The BIOS would detect the remaining SSD, but the PC refuses to boot from it. Rearranging boot device doesn't fix the issue. I could only boot to Windows 11 if I reconnect the SSD with Windo

:)

 

Dual booting OS

Dave is correct, However, If you take ownership of C:\ System (Windows) when you are booted to each OS. Then depending on why you are asking this, as in you do not want others to access the other OS, then Take ownership as mentioned. Then you MUST add your
user name in the list with full permissions/control. Then you would remove all users in the list

EXCEPT KEEP THESE>>YOUR NEWLY ADDED USER NAME, SYSTEM, AUTHENTICATED USERS

REMOVE USERS>>>ADMINS, USERS & EVERYONE

Now for an OS you are booted to. You can add other users in the security users list for C:\ and/or C:\Users & C:\Users\Programs and Programs (x86) & C:\Windows

if there is others with user accounts on that OS. And then grant them the permissions you want to allow.

Because you have removed the user ADMINS, so they need to be granted permissions to access the OS as normal.

Look in Part 2 for detailed steps for ownership, permissions and sharing

https://answers.microsoft.com/en-us...-sharing/fb92e439-5dbc-4367-9857-1ef360e9ffdf

 

Dual booting OS

I updated previous comment.

And then of course, you have to add the dual boot script on each OS i believe when both are on the same drive.

Control Panel\All Control Panel Items\System>>Advanced settings>>Advanced Tab>>

Settings, change display OS to 5 seconds>>OK

Then Environment Variables>>System Variables>>Edit

Now enter the dual boot script and save

But even if you can see the other OS (AKA) other partition, then because it is an OS, you might not be able to access the other OS/Partition. So you can avoid the other procedures. Unless you wanted access, then you can do as explained.

 

Dual boot Phoenix OS

Your question is outside the scope of this Community as Phoenix OS is based on Android platform

But see if this assists you:

How to Install Phoenix OS in Dual Boot Mode with Windows

How to Install Phoenix OS in Dual Boot Mode with Windows

Cheers.