why does bootloader always get messed up when dual boot installing on another drive?

i have windows 11 installed on nvme1, including the efi partition.

the other drives don't have an efi partition.

after removing nvme1, i go and install another version of windows for testing purposes on ssd2 with 90gb unallocated space.
Installation creates the new efi partition, etc on ssd2.

With ssd2 still in the pc, when i put nvme1 back into the pc, it's own efi partition and all, and go to the bios to boot from nvme1, Windows boots into the repair screen.
It fails to boot into windows.

NVME1 and SSD2 each have their own efi partition. So why wasn't windows able to boot into NVME1 ?

NVME1 was removed and untouched during the installation of windows on SSD2.

I had to run the bcdboot command to fix nvme1.

because each time you install Windows that version of Windows tries to take over the boot sequence
the Windows boot-loader doesn't like living with anything else other then the last boot-loader version you installed.

this maybe of interest if you are dual booting with different versions of Windows
Grub2Win

its the Linux GRUB boot-loader for Windows.
best of luck Steve ..

XxXxX said:

because each time you install Windows that version of Windows tries to take over the boot sequence
the Windows boot-loader doesn't like living with anything else other then the last boot-loader version you installed.

this maybe of interest if you are dual booting with different versions of Windows
Grub2Win

Grub2Win

Download Grub2Win for free. ** Support has been added for Endeavour, MX Linux, Pop! OS, Zorin, and CachyOS.

sourceforge.net

its the Linux GRUB boot-loader for Windows.
best of luck Steve ..

Click to expand...

so you're saying I should have deleted the efi partition of the newer windows on ssd2 before trying to boot into nvme1?

if efi on ssd2 is deleted, then it can see my original bootloader in nvme1?

i originally removed the nvme1 drive because when i installed windows on ssd2, it errored in the end due to having too many drives connected.

I would leave NVME1 connected and then boot with the USB to reinstall Windows on the second disk. I would delete all partitions on second disk until all space is unallocated. Then proceed to install Windows on second disk. This should not affect NVME1 but add a second boot entry to boot into the second Windows installation. Only drawback it will make the second installation default and you would have to mark the first one default again.

PS: if the first disk doesn't boot, use the Repair Windows option in the USB.

spapakons said:

I would leave NVME1 connected and then boot with the USB to reinstall Windows on the second disk. I would delete all partitions on second disk until all space is unallocated. Then proceed to install Windows on second disk. This should not affect NVME1 but add a second boot entry to boot into the second Windows installation. Only drawback it will make the second installation default and you would have to mark the first one default again.

PS: if the first disk doesn't boot, use the Repair Windows option in the USB.

Click to expand...

i originally left nvme1 connected when installing windows on ssd2.
but the install failed.

On ssd2 i have a data/storage partition in the back half I don't wanna delete.

i had a total of 5 hard drives connected, and i read that causes windows install to fail.
i guess i'm supposed to disconnect the other 3 drives.

windows was in the process of copying files to ssd2, and then threw an error in the end.

spapakons said:

I would leave NVME1 connected and then boot with the USB to reinstall Windows on the second disk. I would delete all partitions on second disk until all space is unallocated. Then proceed to install Windows on second disk. This should not affect NVME1 but add a second boot entry to boot into the second Windows installation. Only drawback it will make the second installation default and you would have to mark the first one default again.

PS: if the first disk doesn't boot, use the Repair Windows option in the USB.

Click to expand...

100% agreed. By leaving the other drive in, setup will see that there is already an EFI partition present and so it will not need to create another. It will also be able to update the boot config on that drive without creating that on the other drive.

The advice to remove other drives when doing a clean install is just fine for a single installation of Windows, not for dual booting.

Especially when upgrading an unsupported computer, the upgrade might fail if you have two or more disks. Last time I upgraded my father's unsupported computer from 23H2 to 25H2 I disabled the second hard disk in Device Manager. The upgrade completed successfully. The first attempt, to upgrade from 23H2 to 24H2 failed because I hadn't done that.

Did I understand correctly that you currently have Windows 11 installed on NVMe1 and SSD2, but only the installation on NVMe1 boots?

If so, there is no need to delete the EFI partition on SSD2. Windows can have separate EFI partitions on different drives.

If your goal is to add the Windows installation on SSD2 to the boot menu used by NVMe1, run bcdboot against the Windows partition on SSD2 from the Windows installation on NVMe1. For example:

bcdboot D:\Windows

replacing D: with the correct drive letter for the Windows partition on SSD2.

Since you already restored the boot files on NVMe1 with bcdboot, the remaining step is simply to add the second Windows installation to the boot menu if that is your goal.

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...