GRUB unable to detect Windows 11 install

[qsvgxn]

I’m having a hard time doing something that was, in the past, trivial for reasons I’m not getting. I purchased a Lenovo Legion gaming laptop and instantly ripped out the SSD and plugged in a Western digital black 1TB and 2TB high performance samsung, first installed windows onto the 2TB then endeavouros onto the 1TB. Everything worked so perfectly I couldn’t belive it, GRUB entries for all my Linux kernel and a single “Windows” entry for when I want to plug in and do serious gaming.

Unfortunately I dropped my laptop and many keys fell out and cracked the screen, everything worked fine. Lenovo said they’d fix since it’s still in warranty but also said they may have to wipe some disks so back everything. Already have everything that matter on seperate drives anyway so I told them fine.

Laptop gets back and now only has a Windows install on the 2TB. Now I’m pretty sure Lenovo and their technicians probably have nothing to do with this, but for some reason when I went to reinstall EndeavourOS back onto the 1TB, only that works and I cannot get GRUB to detect the Windows 11. Weirdly I can’t even boot into Windows from the UEFI, only the drive for Linux shows up, which I was normally fine with since GRUB could launch Windows anyway but now it’s a problem…

It’s like if I install Windows I can only use that, but if I install Linux onto the 1TB then it locks out Windows since GRUB refuses to detect it. I’m already made sure to uncomment

GRUB_DISABLE_OS_PROBER=false
in my /etc/default/grub but still nothing.

Can anyone please help me? Here is also the output of lsblk -fs

NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
sda
└─sda1 vfat FAT32 ESD-USB 0AB0-7DB2
nvme0n1
├─nvme0n1p1 vfat FAT32 F0D4-F188 2G 2% /boot/efi
└─nvme0n1p2 ext4 1.0 endeavouros 04acf9ad-eea3-41fa-aaf3-054b7833d3c8 857.7G 1% /
nvme1n1
├─nvme1n1p1
├─nvme1n1p2 BitLocker 2 [MYNAME]-WINDOWS C: 9/2/2025 fa730906-54bc-4d51-a3bf-b73242b248b1
└─nvme1n1p3 ntfs 963CA0053C9FDF15

[Greymane]

Is it possibly you installed Eos in legacy instead of gpt? See this thread….it is for fedora but same principle applies to Eos.

Windows 11 not showing up in Grub after trying to dual boot

[qsvgxn]

I definitely install EOS in GPT mode. I don’t think there was any other option.

[keescase]

Welcome to the forum

Did you also remember to do this ?

sudo grub-mkconfig -o /boot/grub/grub.cfg

[SdW]

I bought a Lenovo Thinkpad 1 a few years back with Windows 10 preinstalled. The setup was downright dictatorial about booting Windows and not grub. I had to rename and move a grub boot file to the Windows boot directory (and delete the Windows boot file I was replacing) to get grub to boot up. It’s been too long to remember the name of the file. Another trick that worked was to install EOS on a separate disk and then give that disk boot priority in the BIOS.

You might try to erase the disk entirely, reinstall both Windows and EOS in that order. Be sure to give EOS its own EFI partition. I think it was probably Lenovo that hard-coded the Windows boot file name; the problem was unique to them. If you just install EOS after erasing the disk completely, grub boots up just fine.

Hope this helps, wish I could remember the exact file, but perhaps it has changed in Win 11 anyway.

[xircon]

Is os-prober installed? From (my bad) memory, it was not installed by default anymore??

:Edit:
Bottom of /etc/default/grub set true to false:

GRUB_DISABLE_OS_PROBER=false

Then rebuild (edited repeatedly as I am half asleep )

[qsvgxn]

Oh jeez please don’t be mad but I think I’ve solved the issue and it’s very silly.

I turned off the Bitlocker Encryption and just like that os-prober can see everything and all commands are working again. I think that really was the only issue was just having that flipped back on without me knowing it, since it hides the EFI partition as well.