Dual-boot troubles with Windows 11 and BitLocker

I need help figuring out what happened and what to do.
A far away relative has a Windows 11 PC that got too bloated, high CPU, freezes…
I tried fixing it earlier but gave up.
Since I don't have the time there to sort things, I thought I would install a new drive as a dual boot system, as I have done multiple times in the past decades.
The two old drives were 2.5" SATAs, and the new one is an NVMe. The PC is fully compatible with Windows 11, which I verified with the MS tool as well. I believe the old drive did not have BitLocker enabled, and while I saw an MS account, it required no password anywhere - not even for administrator options.
I first tried a Rufus made USB drive with MS account and BitLocker disabled, to try avoiding problems, but the install kept failing, on both Windows 11 installers, 2 latest versions of Win ISO, 2 versions of Rufus, online and offline, removing hardware… eventually I only managed to install it after making a new USB with nothing removed and disconnecting both old drives, as many wrote solved it for them. I used the MS account from the other install, I believe.
However, after re-connecting the old drives, now I have no boot menu *and* it requires BitLocker code to access the old drives from the F8 menu. I could find the code @ MS, it's dated new BTW, but we need to type it all every time, and then the new drive is locked for it.
I tried from the installer's terminal (after typing the BootLocker codes) the: bootrec /fixmbr /fixboot /scanOS /rebuildbcd. It found 3, but I can see no change.
Why? How can I fix that? I don't need the BitLocker. I hope for both OS working and for the menu. Or at least just have the old OS back working as normal.
Thank you for any help!

Any relatively safe path, that won't make things harder?

you can disable/turn off bit locker in settings > security
then the drive will un-encrypt itself.

you can also find your bitlocker keys in the control panel > bitlocker encryption
before you remove the encryption from the drive.

best of luck Steve ..

TKR said:

I don't need the BitLocker.

Click to expand...

Go to:

Settings > Privacy & security > Device encryption

Turn it Off.

TKR said:

bootrec /fixmbr /fixboot

Click to expand...

These commands are intended for legacy BIOS/MBR-based systems. They are not compatible with boot repairs on UEFI/GPT configurations, where the UEFI firmware loads EFI executables (.efi) directly from the FAT32-formatted EFI system partition, bypassing traditional MBR/VBR boot sector chaining.

bootrec /FixMbr

• Writes a Windows-compatible Master Boot Record (MBR) to sector 0 of the system disk.
• On UEFI/GPT systems, this only updates the Protective MBR and does not repair the actual UEFI boot process.

bootrec /FixBoot

• Writes a new Volume Boot Record (VBR) to the system partition, using a boot sector compatible with the current version of Windows.
• In Windows 10 (version 1709 and later) and Windows 11, the bootrec /fixboot command no longer works in the Windows Recovery Environment (WinRE), regardless of whether the disk uses GPT or MBR. Running the command results in an "Access is denied" error.

TKR said:

/rebuildbcd. It found 3, but I can see no change.

Click to expand...

This means that the command found three Windows installations missing from the BCD store.

bootrec /RebuildBcd
- Scans all disks for Windows installations that are not currently present in the Boot Configuration Data (BCD) store.
- Prompts the user to add the detected installations to the BCD store.
- If "Total identified Windows installations: 0" is reported, it means no Windows installations were found that are missing from the BCD store.

TKR said:

after re-connecting the old drives, now I have no boot menu

Click to expand...

Run the following command as an administrator, replacing x with the Windows partition letter (e.g. bcdboot d:\windows):

bcdboot x:\windows

Note: The primary C:\Windows partition is already in the BCD store and does not need to be added.

When setting up a PC to boot more than one operating system, you may sometimes lose the ability to boot into one of the operating systems. The BCDBoot option allows you to quickly add boot options for a Windows-based operating system.

Click to expand...

There are a number of approaches to this problem. Myself, I like the quick and fast and possibly dirty approach until I can get things 'ironed out' as it were.

Keep in mind that only one activation key can be used per OS. Neither can you boot to a clone of the same OS when the original OS is running on the unit. This will result in a conflict and you won't be able to boot to either. Here is what I do to get booting in dual boot before I start doing surgery i.e. removing BitLocker, Co-Pilot, One Drive etc.

1) Disconnect all drives that refuse to boot and work only with the drive that allows you to access the OS.
2) Boot up to that OS and download Easy BCD here >> Easy BCD
3) Install Easy BCD
4) Reboot and configure BCD (It's extremely user friendly and very easy to configure.)
5) Shut down computer and reconnect the drives you want to boot to
6) Start PC and select the working OS and boot to it
7) Use Disk Manager to find the drive letters of the drives you wish to boot to.
8) Enter those drive letter into the Easy BCD configuration list.
9) Reboot - you should have more than one selection to chose from on a boot screen

Let us know if you can boot to any of those other drives after doing the above.

Thank you all. I will try this as soon as I can get my currently busy relative to try.

XxXxX said:

you can disable/turn off bit locker in settings > security
then the drive will un-encrypt itself.

Click to expand...

Would the one switch work for all 3 drives at once, and from any of the 2 bootable (one easy, one hard) Win11 operating systems? Any preference from where, since the new one should be actually encrypted?

Scannerman said:

There are a number of approaches to this problem.

Click to expand...

So, to make sure I got this right, I should do 2 separate things to fix that:

• disable BitLocker
• fix BCD in one of the above ways

And the order does not matter, only for convenience?

Scannerman said:

Keep in mind that only one activation key can be used per OS. Neither can you boot to a clone of the same OS when the original OS is running on the unit

Click to expand...

Sure, we only need one OS working at a time, nothing special.

TKR said:

So, to make sure I got this right, I should do 2 separate things to fix that:

• disable BitLocker
• fix BCD in one of the above ways

And the order does not matter, only for convenience?

Click to expand...

ChatGPT:

Technically, the order usually does not matter. The two tasks are mostly independent:

• disabling BitLocker affects drive encryption/unlocking
• repairing the Boot Configuration Data affects the boot menu and boot entries

However, for convenience and to avoid confusion, it is generally better to:

1. unlock/disable BitLocker first
2. then repair the BCD

Click to expand...

TKR said:

So, to make sure I got this right, I should do 2 separate things to fix that:

• disable BitLocker
• fix BCD in one of the above ways

And the order does not matter, only for convenience?

Click to expand...

Myself, I would do the BCD bit first before disabling BitLocker but it probably wouldn't matter if you can already access the OS.

TKR said:

Sure, we only need one OS working at a time, nothing special.

Click to expand...

Every OS will need it's own activation key.