Hi
I’m new to Linux and installed Manjaro last night on my computer already running windows 10. I installed updates and one kernel update. Afterwards when I try to reboot system grub didn’t show up and memtest screen showed. When I closed memtest the system rebooted and didn’t boot to any os. I then booted the system with manjaro live usb but couldn’t find anything to rescue grub since I have little linux command then I booted with the windows 10 rescue disk and run bootrec /fixmbr command to let windows 10 boot. But grub is gone. How can I reinstall grub? Thanks.
Hi @cmlc, and welcome!
I suspect this can be fixed with a chroot. The steps:
- Download the latest ISO, burn it onto a USB, then boot into the Manjaro live ISO enviroment.
- Once succeessfukky booted into the live ISO environment, open a terminal and enter a chroot environment by running,
manjaro-chroot -a
If there is only the one Linux installation present on your computer, this should work and be all that’s neccesary. Theoretically.
-
If successful, you are now in a
chrootenvironment. Be careful from here on, seeing as you are now logged in as root on your computer. -
You should now be able reinstall grub. To do so run,
pacman -Syu grub
From here on, I’m not 100% sure, so I can exactly say if it’ll be neccessary or not. But just to be on the safe side, edit /etc/default/grub:
nano /etc/default/grub
And make sure GRUB_DISABLE_OS_PROBER is specified and set to `false:
GRUB_DISABLE_OS_PROBER=false
-
Save and exit.
-
Back on the command line, still in the chroot environment, run:
update-grub
- If successful, leave the chroot environment, hold your thumbs while dancing on one leg, recording it for youtube and providing us with the link, then reboot.
In theory, you should have your grub back and you can, and should feel free to heap on the praise. If not, well, then I’m innocent because, well, I aint done nottin’ sarge!
Edit:
Also see: GRUB/Restore the GRUB Bootloader - Manjaro
Also, if you want, this could, in theory, be an ideal time to see if you can use, and install another boot loader, like rEFInd.
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Thank you very much. I’ll try it when I get home.
I’m also thinking of backing up the small boot partition which is used by both windows and manjaro grub to boot to using some imaging program just in case to restore .
IIRC, that is actually how it works with Linux. (I have absolutely no idea how Windoze does it.)
The important things to remember, is the config file is /etc/default/grub, os-prober is necessary for dual-boot, and very important, after every change in the config file you need to run update-grub. Or you can just switch to rEFInd, of which I can tell you 1 thing only, and that’s that it is a boot loader as well.
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Maybe your Grub-menu is just hidden. Did you try pressing ESC or holding Shift during boot (usually those need to be pressed a few seconds into the first splash screen)?
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Thanks. Will rEFInd work with my old mbr system?
Not 
% sure, but unfortunately I don’t think so.
Nope I didn’t and cannot try anymore since grub is gone. But these are valuable information, thanks. I have very little linux command. I want to to start to learn linux with manjaro. I tried garuda linux but it is heavy on resources and unnecessarily complex.
Nope, it only works with EFI system and GPT partition tables.
GPT switching is fairly easy but you have to wipe all your disk. BIOS to UEFI, depends of your hardware. I just discovered one week ago I could boot my 2011 BIOS laptop into UEFI too.
In REFind, you have EFI.
That’s how I understood it, but now I can know it.
The point is if grub is configured to be hidden, then it appears to be gone, but you just have to invoke it during boot by pressing one of those keys 
Memtest is one of the boot options within grub’s menu, so maybe it just defaulted to booting memtest…
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One more question, Is the Grub Customizer software compatible with manjaro?
That’s debatable…Apparently. It was blocked for causing problems, but apparently it has since been unblocked, so I think it’s better now. Not sure.
So I don’t recommend it. Doing thing manually forces you to learn more, anyway.
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I tried those but grub still won’t show up. I noticed that the grub file is still on manjaro and I edited the file and updated but still no boot.
If you followed the instructions and it still won’t boot, it had to have given you an error somewhere.
And, sadly, without knowing what’s going on, nobody will be able to help you, so you’d need to give us more information. Specifically the error(s) you’'re getting.
I’ll try once more and post the terminal screen output when I get home.
By the way a new testing release is out. Would I install that ?
If you’re sure yoour data is safe and so on, give it a go and see what happens.
[manjaro@manjaro ~]$ manjaro-chroot -a
grub-probe: error: cannot find a GRUB drive for /dev/sde1. Check your device.map.
grub-probe: error: cannot find a GRUB drive for /dev/sde1. Check your device.map.
==> Detected systems:
--> 0) Windows
--> 1) ManjaroLinux
==> Select system to mount [0-1] :
1
==> Mounting (ManjaroLinux) [/dev/sda4]
--> mount: [/mnt]
mount: /mnt: /dev/sda4 already mounted on /mnt.
[manjaro /]# pacman -Syu grub
:: Synchronizing package databases...
core is up to date
extra is up to date
community 6.6 MiB 193 KiB/s 00:35 [##################] 100%
multilib is up to date
warning: grub-2.04-21 is up to date -- reinstalling
:: Starting full system upgrade...
resolving dependencies...
looking for conflicting packages...
Packages (2) inxi-3.3.03.1-1 grub-2.04-21
Total Download Size: 0.28 MiB
Total Installed Size: 49.83 MiB
Net Upgrade Size: 0.00 MiB
:: Proceed with installation? [Y/n] y
:: Retrieving packages...
error: failed retrieving file 'inxi-3.3.03.1-1-any.pkg.tar.zst' from mirror.23media.com : Resolving timed out after 10000 milliseconds
inxi-3.3.03.1-1-any 290.6 KiB 62.7 KiB/s 00:05 [##################] 100%
(2/2) checking keys in keyring [##################] 100%
(2/2) checking package integrity [##################] 100%
(2/2) loading package files [##################] 100%
(2/2) checking for file conflicts [##################] 100%
(2/2) checking available disk space [##################] 100%
:: Processing package changes...
(1/2) reinstalling grub [##################] 100%
(2/2) upgrading inxi [##################] 100%
:: Running post-transaction hooks...
(1/2) Arming ConditionNeedsUpdate...
(2/2) Updating the info directory file...
[manjaro /]# nano /etc/default/grub
[manjaro /]# nano /etc/default/grub
[manjaro /]# update-grub
Generating grub configuration file ...
Found theme: /usr/share/grub/themes/manjaro/theme.txt
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
Found linux image: /boot/vmlinuz-5.4-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.4-x86_64.img
Found initrd fallback image: /boot/initramfs-5.4-x86_64-fallback.img
grub-probe: error: cannot find a GRUB drive for /dev/sde1. Check your device.map.
grub-probe: error: cannot find a GRUB drive for /dev/sde1. Check your device.map.
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 10 on /dev/sda1
Found memtest86+ image: /boot/memtest86+/memtest.bin
done
[manjaro /]#
Could you post the output of head -n 5 /etc/default/grub?
GRUB_DEFAULT=2
GRUB_TIMEOUT=3
GRUB_TIMEOUT_STYLE=menu
GRUB_DISTRIBUTOR=“Manjaro”
GRUB_CMDLINE_LINUX_DEFAULT=“quiet apparmor=1 security=apparmor udev.log_priority=3”