Windows bootloader not found in grub or os-prober

Hello dear Community,
does anyone has an idea why os-prober does not show the windows bootloader? grub(before), grub-rescue and the bios can see it but can not boot it. With grub-install I just got grub-rescue because it seems like mine just wants only eos as its efi bootlader. Even If I start from the Windows Bootloader it wont like the bootloader was deleted. The partition table shows that the Windowsbootlloader is there.This problem came as wndows got update as I was booting up. The restart started autmatically and the problem began.

Best ragards,
TerminalNinja aka. Viet

ps. I am really happy to be in this friendly community <3.

You’re going to have to search though posts like this. Windows dual booting linux with grub is always a problem. You should really use two separate drives.

Also, you could post some “hard” info about your system:

  1. test -d /sys/firmware/efi && echo UEFI || echo BIOS

  2. efibootmgr -v

  3. sudo parted -l

Hopefully this will give someone on the forum some ideas to start helping you troubleshooting.

One way around it is to drop grub entirely :grin: You could try rEFInd (see our wiki) it would only take a minute to find out if it will work easily - two commands and reboot! (install package, and run refind-install). Most of the Windows dual boot problems I’ve seen are ignored in rEFInd…

#test -d /sys/firmware/efi && echo UEFI || echo BIOS
#efibootmgr  -v
BootCurrent: 0001
Timeout: 0 seconds
BootOrder: 0001,001B,0000,0017,0016,0019,0018,001A,001C
Boot0000* Windows Boot Manager	HD(1,GPT,df78a729-da8b-4a7b-a94e-0948311b9b17,0x800,0x32000)/File(\EFI\Microsoft\Boot\bootmgfw.efi)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.}...M................
Boot0001* endeavouros	HD(5,GPT,50728230-a032-b941-8c12-15112071516a,0x1e41ef40,0x960c0)/File(\EFI\endeavouros\grubx64.efi)
Boot0010  Setup	FvFile(721c8b66-426c-4e86-8e99-3457c46ab0b9)
Boot0011  Boot Menu	FvFile(126a762d-5758-4fca-8531-201a7f57f850)
Boot0012  Diagnostic Splash Screen	FvFile(a7d8d9a6-6ab0-4aeb-ad9d-163e59a7a380)
Boot0013  Lenovo Diagnostics	FvFile(3f7e615b-0d45-4f80-88dc-26b234958560)
Boot0014  Startup Interrupt Menu	FvFile(f46ee6f4-4785-43a3-923d-7f786c3c8479)
Boot0015  Rescue and Recovery	FvFile(665d3f60-ad3e-4cad-8e26-db46eee9f1b5)
Boot0016* USB CD	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,86701296aa5a7848b66cd49dd3ba6a55)
Boot0017* USB FDD	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,6ff015a28830b543a8b8641009461e49)
Boot0018* NVMe0	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,001c199932d94c4eae9aa0b6e98eb8a400)
Boot0019* NVMe1	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,001c199932d94c4eae9aa0b6e98eb8a401)
Boot001A* ATA HDD0	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,91af625956449f41a7b91f4f892ab0f600)
Boot001B* USB HDD	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,33e821aaaf33bc4789bd419f88c50803)
Boot001C* PXE BOOT	VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,78a84aaf2b2afc4ea79cf5cc8f3d3803)
Boot001D  Regulatory Information	FvFile(478c92a0-2622-42b7-a65d-5894169e4d24)

#sudo parted -l
Modell: WDC PC SN530 SDBPMPZ-512G-1001 (nvme)
Festplatte  /dev/nvme0n1:  512GB
Sektorgröße (logisch/physisch): 512B/512B
Partitionstabelle: gpt

Nummer  Anfang  Ende   Größe   Dateisystem  Name                          Flags
 1      1049kB  106MB  105MB   fat32        EFI System Partition          boot, esp
 2      106MB   123MB  16,8MB               Microsoft reserved partition  msftres
 3      123MB   260GB  260GB   ntfs         Basic data partition          msftdata
 5      260GB   260GB  315MB   fat32                                      msftdata
 6      260GB   512GB  251GB   btrfs
 4      512GB   512GB  540MB   ntfs                                       versteckt, diag

#cat /etc/default/grub
# GRUB boot loader configuration

GRUB_CMDLINE_LINUX_DEFAULT="quiet loglevel=3 nowatchdog"

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable booting from LUKS encrypted devices

# Set to 'countdown' or 'hidden' to change timeout behavior,
# press ESC key to display menu.

# Uncomment to use basic console

# Uncomment to disable graphical terminal

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'

# Uncomment to allow the kernel use the same resolution used by grub

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"

# Uncomment to disable generation of recovery mode menu entries

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.

# Uncomment one of them for the gfx desired, a image background or a gfxtheme

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

# Uncomment to make GRUB remember the last selection. This requires
# setting 'GRUB_DEFAULT=saved' above.

# Uncomment to disable submenus in boot menu

Terminal out put can be copy and pasted no pictures please.

What is the output of

cat /etc/default/grub


Please copy the terminal output as text and paste it into your reply, highlight it and use the </> button to format.

It is nice to have but I prefer using grub which has lesser probs as with REFIND. I used it on FreeBSD where it’s causes more probs when you are using snapshots in grub

I correct it on my last reply.


My English language knowledge does not seem capable to understand what exactly you want to fix.
Can you please explain simpler?

Can you boot to Linux?
Can you boot to WinOS?
If you can boot to Linux, is it in UEFI?
Is winOS in UEFI or MSDOS/Legacy boot mode?

Usual problems with Win updates are mostly fixed with re-installing grub, or replacing default EFI file with EnOS/grub efi file. Archwiki explains most of these issues.

There are also way too many unneeded entries in efibootmgr.

Is this the default package file, or how was it modified?
Remove quoting from the above values, since they are booleans. I don’t know if this breaks os-prober enable value, but it could certainly be.

They seem to be Vendor’s entries, or some very talented Win program :smile: .

It is booting on UEFI as you see on the cmd line. I can only boot on the EOS and other OSes which are not Windows. I think it is something with GPT instead of mbr. Windows hast alot of probs with gpt.

Edit: I find that strange.

I use rEFInd and there are no boot issues.

We need an answer on this :point_up:

  • Do you mean there was a WinOS entry in grub menu?
  • Have you ever booted to WinOS from a grub menu entry?
  • Is it a new installation?
  • Have you ever dual-booted Linux and WinOS on this PC/laptop (you should have posted your system info inxi -Faz) ?
  • Post output of this:
sudo os-prober

Since you want help, you should answer all questions you are asked for. Why not???

I see Windows the EFI and i see another fat32 partition which means likely EOS is installed in MBR mode? Maybe?

 1      1049kB  106MB  105MB   fat32        EFI System Partition          boot, esp   
 5      260GB   260GB  315MB   fat32                                      msftdata

UEFI will not add an Mbr installed system to grub.

Do you have secure boot disabled and CSM turned off in the Bios when you installed EOS. If EOS is not installed in UEFI mode you will need to install it properly. If you used the erase disc and automatic install then likely you had CSM on and it installed in Mbr mode?

Edit: If you are able to boot into EOS & did you try updating grub?

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