GRUB stands for GRand Unified Bootloader, which is invoked by BIOS to load multiple kernel (if exist) and displays a boot menu for users to choose from. It's similar to NTLDR or BOOTMGR for Windows, but supports both Windows and Linux kernel, and comes with more features. However, if you haven't configured Grub properly, you will encounter GRUB errors like those described below.
Grub Loading Error 15, 17, 21, 22?
For Grub Stage 1, there are no error numbers, just "Hard Disk Error", "Floppy Error", "Read Error", or "Geom Error". Hence, if you get an error number, you are probably using Grub Stage 1.5 or Stage 2.0. So, what's the Grub loading error number mean in order to get a clue to resolve the problem. See below:
Grub loading error 15 : File not found. This error is displayed when the specified file name cannot be found.
Grub loading error 17 : Cannot mount selected partition. This error is displayed when the partition requested exists, but the file system type cannot be recognized by GRUB.
Grub loading error 21 : Selected disk does not exist. This error is displayed if the disk is not recognized by the BIOS in the system.
Grub loading error 22 : No such partition. This error is displayed if a requested partition isn't on the selected disk.
How to Fix Grub Loading Error
Here simple solutions are given as below for all popular grub loading errors.
Grub loading error 15: Make sure the kernel exists. To find out what the exact kernel name is, boot from the live CD, and mount /boot or / depending on your partition and then do the following: cd /boot | ls
Grub loading error 17: Make sure your root(x,y) settings are right in your grub.conf. You could use a distribution CD or Live CD to set up Grub as below. (h0,0) means the first hard drive and the first partition on that drive.
Grub loading error 21: Make sure the disk is correctly connected and detected by the BIOS.
Grub loading error 22: You could use the Windows Installation Disc to run a Startup Repair and fix MBR.
The Grub loading error generally occurs when Grub is trying to load a non-Windows system. So you could fix the MBR with Startup Repair option in Windows Installation Disc, and then re-install Grub for Unix-like systems with the distribution CD or Live CD.
If you have no Windows Installation Disc, borrow one or use PowerSuite Golden which allows you to boot any computer for fixing errors and installing a new Windows system. PowerSuite Golden has intuitive graphic interface and is extremely easy to use.
1. Create a Bootable CD/DVD/USB on another PC to boot any computer.
2. Fix MBR in Boot Crash Solution.
3. Re-install and configure Grub properly to load all systems installed in your hard drive.