Fixing Manjaro's Grub Configuration to allow os-prober to find Windows 10
I run a dual boot setup on one of my main work machines, with Manjaro Linux sharing a home with a Windows 10 installation. Manjaro has been pretty good at insulating me from a lot of the day-to-day maintenance issues that I have unfortunately come to expect with most Linux distros, but it is certainly not without issues and quirks.
Last week I updated grub through pacman and discovered that the next time I rebooted, my Windows 10 installation had vanished from the Grub bootloader.
I ran sudo update-grub expecting it to fix the issue but found it did not.
I did notice this line in the output which clued me in to the issue:
[manjaro ~]$ sudo update-grub Generating grub configuration file ... Found theme: /usr/share/grub/themes/manjaro/theme.txt Found linux image: /boot/vmlinuz-5.11-x86_64 Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.11-x86_64.img Found initrd fallback image: /boot/initramfs-5.11-x86_64-fallback.img Found linux image: /boot/vmlinuz-5.10-x86_64 Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.10-x86_64.img Found initrd fallback image: /boot/initramfs-5.10-x86_64-fallback.img Found linux image: /boot/vmlinuz-5.9-x86_64 Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.9-x86_64.img Found initrd fallback image: /boot/initramfs-5.9-x86_64-fallback.img Warning: os-prober will not be executed to detect other bootable partitions.Systems on them will not be added to the GRUB boot configuration. Check GRUB_DISABLE_OS_PROBER documentation entry. Adding boot menu entry for UEFI Firmware Settings ... Found memtest86+ image: /boot/memtest86+/memtest.bin done
The important bit is the warning, which indicates that for some reason os-prober was not run.
Luckily, I was able to find the fix on this reddit post.
You simply have to edit /etc/default/grub
and add the line:
GRUB_DISABLE_OS_PROBER="false"
I also mounted my Windows partition for good measure, since some comments on Stack Overflow seemed to imply that this is necessary in order for os-prober to find other installations.
After that, I ran sudo update-grub and found that the issue was fixed!
[manjaro ~]$ sudo update-grub Generating grub configuration file ... Found theme: /usr/share/grub/themes/manjaro/theme.txt Found linux image: /boot/vmlinuz-5.11-x86_64 Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.11-x86_64.img Found initrd fallback image: /boot/initramfs-5.11-x86_64-fallback.img Found linux image: /boot/vmlinuz-5.10-x86_64 Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.10-x86_64.img Found initrd fallback image: /boot/initramfs-5.10-x86_64-fallback.img Found linux image: /boot/vmlinuz-5.9-x86_64 Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.9-x86_64.img Found initrd fallback image: /boot/initramfs-5.9-x86_64-fallback.img Warning: os-prober was executed to detect other bootable partitions.It's output will be used to detect bootable binaries on them and create new boot entries. Found Windows Boot Manager on /dev/sdb2@/EFI/Microsoft/Boot/bootmgfw.efi Adding boot menu entry for UEFI Firmware Settings ... Found memtest86+ image: /boot/memtest86+/memtest.bin done
Hope this helps someone!