GNU GRUB blocks screen after update.

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923
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GNU GRUB blocks screen after update.

Post by 923 » Mon Feb 26, 2018 10:47 pm

I ran the update and let all files download. After some minutes suddenly a black screen occurred with GNU GRAB prompt. I don't know how to proceed from here. Is there anything to be typed here to finalize he update?

This is the text prompted on the black screen:

GNU GRUB version 2.02 beta2-36ubuntu3.17
Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else FAB lists possible device or file completions.

grub>

fabien85
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Re: GNU GRUB blocks screen after update.

Post by fabien85 » Tue Feb 27, 2018 5:01 am

Grub is the bootloader, the very first program that starts.
So if you get to the grub prompt, it means your computer rebooted and somehow grub didnt find the configuration file which tells it what system to boot.
Why it rebooted ? That's the good question. If you didnt do it yourself, then there is a problem somewhere in the system.

From the grub command line, you should be able to boot your system back with a bit of search.
See the following page for instructions : https://help.ubuntu.com/community/Grub2 ... #grub.3E-1

Basically start by issuing

Code: Select all

configfile /boot/grub/grub.cfg
(and press enter). If that works, you will get to the grub menu where you have an entry to boot Mint.
If that doesnt work it means you have to find the linux root partition. Use the section Search&Set of the link above to do so. Basically you first issue ls to see what are the present drives (usually there is just one), then ls (hd0) to see what partitions are on the first drive, see if there is one you think is the root : it should be formatted as ext4 filesystem for a default install (and for a default install, that's the only such partition), then you look whether the file /boot/grub/grub.cfg is present on that root partition and if so you load it, otherwise you will have to directly load the kernel and initrd image.

923
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Re: GNU GRUB blocks screen after update.

Post by 923 » Wed Feb 28, 2018 11:23 pm

Hi fabien85, thank you very much for this advice. It solved the problem to the extent that the system is booting again after typing "configfile /boot/grub/grub.cfg" in grab. One the second attempt it started the usual menu to select the OS and per default it started Linux Mint. Upon restart however the Grub black screen appeared again and I have to input "configfile /boot/grub/grub.cfg" on every start now. May I ask, is there a way to permanently fix this?

fabien85
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Re: GNU GRUB blocks screen after update.

Post by fabien85 » Thu Mar 01, 2018 5:43 am

Indeed the workaround is to allow you to boot once, but we need to fix grub so that this becomes permanent.
The simplest is to reinstall grub completely.
If your computer has a single hard drive, then it's simple :
Boot Mint, open a terminal and issue

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sudo grub-install /dev/sda
If you have several hard drives, it becomes more complicated as we have to find on which one grub is installed.
Please provide the output of the following terminal commands

Code: Select all

blkid
dpkg --get-selections | grep grub
sudo os-prober
sudo parted --list
Please put the output between code tags (button </> above the typing area), for readability.
These info will help us to tell you how to reinstall grub.

When your system is back to normal, I would do a backup and check the state of the disk(s).

923
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Re: GNU GRUB blocks screen after update.

Post by 923 » Sun Mar 04, 2018 12:22 am

Thank you very much, fabien85. That worked very well with reinstalling grub. Everything is working again. The hard drive is old and about to give up. I guess that caused this issue.

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