You switch on a Linux machine and instead of your desktop you get a stark text prompt that reads grub rescue>, or an error about no bootable device, or a screen that hangs partway. It looks far more serious than it usually is. Linux boot problems tend to come from a small set of well-understood causes, and most are fixable without losing anything. Here is how to approach them in plain terms.
Understanding what GRUB is
GRUB is the bootloader: the small programme that runs first and loads your Linux system. When you see a GRUB error, it almost always means GRUB itself cannot find or load the system it is supposed to start. The system on the drive is usually still intact; it is the signpost pointing at it that has gone wrong. That distinction matters, because it means your data is very often safe.
Check the boot order first
Before assuming GRUB is broken, rule out the simplest cause. A "no bootable device" message often just means the machine is trying to boot from the wrong drive, especially after a power cut, a BIOS reset, or plugging in a USB stick. Enter your BIOS or UEFI settings (usually by tapping Del, F2, F10 or F12 as the machine starts), check the boot order, and make sure your main drive is first. Remove any USB sticks and try again.
The GRUB rescue prompt
If you land at grub rescue>, GRUB started but lost track of where its files are, often after another operating system was installed alongside, or a partition changed. From the prompt you can list partitions and point GRUB at the right one to boot once:
| Command | What it does |
|---|---|
| ls | Lists the drives and partitions GRUB can see |
| set prefix=(hdX,Y)/boot/grub | Tells GRUB where its files live |
| set root=(hdX,Y) | Sets the partition to boot from |
| insmod normal | Loads the normal boot module |
| normal | Resumes a normal boot |
This gets you booted once. It is a temporary fix; you still need to reinstall GRUB properly afterwards so it survives the next restart, which is best done from a live USB as below.
Recover with a live USB
The most reliable way to fix a broken bootloader is to boot from a live USB of your distribution, the same kind of stick you would install from. From the live session you can mount your real system and reinstall GRUB cleanly. The general approach is to mount your root partition, bind the system folders, change into it with chroot, then run the distribution's GRUB install and update commands (such as grub-install and update-grub on Debian and Ubuntu-based systems). Done correctly this rebuilds the bootloader and detects every system on the machine. If those steps are unfamiliar, this is a sensible point to get a hand rather than risk the partitions.
Broken packages after an update
Sometimes the machine boots but stalls, or an update was interrupted partway and left the system in a half-finished state. Boot into recovery or a text console and repair the package system. On Debian and Ubuntu-based systems the usual repair is sudo dpkg --configure -a followed by sudo apt --fix-broken install, which completes the interrupted work. A kernel update that did not finish cleanly is a common reason a machine that was fine yesterday will not boot today.
Check the filesystem
If the boot stops with errors about the filesystem, or after an unclean shutdown such as a loadshedding power cut, the filesystem may need checking. From a live USB or recovery console you can run fsck on the affected partition (never on a mounted one) to find and repair errors. This resolves many "drops to a prompt during boot" situations, particularly after sudden power loss, which is worth bearing in mind on the South Coast.
When it is the hardware
If the drive is not detected in the BIOS at all, makes clicking or grinding noises, or fsck finds widespread unrepairable errors, you are likely looking at a failing drive rather than a software fault. At that point the priority shifts to recovering your data safely before anything else. Hardware faults need proper testing to confirm, and a dying drive should be handled carefully to give your files the best chance.
When to bring it in
Linux gives you powerful recovery tools, but bootloader surgery and filesystem repair carry real risk if a command goes wrong, and a suspected drive failure is not the moment to experiment. If you would rather not gamble with your data, we work across Windows, Mac and Linux, and we can recover your files, repair the boot, or confirm a hardware fault and quote you before any work. See what our computer repairs cover, and our wider services including data recovery.
We have sorted out boot and drive problems across every kind of machine on the South Coast since 2010, and your data always comes first. Call 039 314 4359 to talk it through, or book a repair and we will take a look.
