The primary reason for this error is that your grub boot loader configuration has been tampered with, corrupted, misconfigured or deleted. More specifically, you might have forcefully deleted your Ubuntu or some other Linux system files from a dual boot PC, or you extended certain disk partition into the partition with your Grub boot loader.
Grub boot loader provides you the choice to boot one of multiple operating systems installed on your computer, hence corrupting the boot loader prevents you from accessing any of the installed operating system even if such operating system is still functional. Hence you get this Grub error during startup: “error: no such partition. Entering rescue mode…Grub rescue>”.
The tutorials linked below could also help you in preventing the recurrence of this issue and possibly serve as solutions to the current issue.
- How to Remove (uninstall) Linux (Ubuntu) From Dual Boot in Windows 10.
- How to Install Windows 10 From a USB Flash Drive | Step by Step + Free Activation.
- How To Fix Bootrec /fixboot Access is Denied During Fix Boot Configuration (2 Fixes )
The following methods were covered in this video:
Method 1: Manually Reconfiguring GRUB Bootloader.
Method 2: Rebuilding the Boot Configuration Data files (BCD) using the bootrec tool in windows.
Method 3: Use the registry backup command called regback to replaces your registry configuration with the last known good configuration you have on your PC.
METHOD 1: Manually Reconfigure Grub Boot Loader
This would require locating the partition with your Windows installation or whatever operating system you want to restore as your primary boot OS. To do this, while on this screen with the error message, type the command: “ls” and hit enter. This will display all the partitions you currently have on your disk.
In this case I have just 2 partitions, yours might be more, but in any case you will need to check and see which of the listed partitions has your operating system installed on it. You can start with the Msdos1 partition or whichever partition you want.
So to check if is in the msdos1 partition, type the command, “ls (hd0,msdos1)” and hit enter. If you get a note saying file system is unknown, then is not the partition you’re looking for and you should run a similar command for the other partitions you have.
If you get a message saying something like, “file system is ext2 or ext3” from any of your partitions, then that is the partition you’re looking for. This ext file is the extended file system for your Linux kernel and that is the partition with your operating system.
With that run the following commands:
- “set boot=(hd0,msdos5)”(Replace “msdos5” with the partition where you found your operating system)
- “set prefix=(hd0,msdos5)/boot/grub”
- “insmod normal”,
That should resolve the issue and boot back to your operating systems.
However, if all the partitions say “unknown”, then type the command “set” and hit enter. It should show if there is another hidden partition where you have an operating system, here the hidden partition is labeled msdos5. Now type the command “set boot=(hd0,msdos5)” and hit enter.
Next type “set prefix=(hd0,msdos5)/boot/grub” and hit enter. Then type “insmod normal” and hit enter. Lastly type “normal” and hit enter to complete the process
METHOD 2: Rebuilding the Boot Configuration Data File (BCD) using the Bootrec Tool.
Here we will be rebuilding the Boot Configuration Data files (BCD) using the bootrec tool in windows. The bootrec tool tries to locate any windows installations on all disks attached to your computer and then add them back to the boot list so the boot manager can locate them during startup.
To do this you will need a bootable USB with windows 10 installation files. Attach your Windows 10 USB stick and press the power button on your computer to start the process. Using the corresponding function keys or combination of escape and function key, select your boot device to boot from the USB.
On this initial set-up page select Windows 10 64-bit or 32-bits depending on your platform. Then wait for the installation files to load
On the page that follows, select next
Then click on repair your computer.
then select troubleshoot,
and then click on command prompt.
Then type the command bootrec /fixmbr and hit enter. It should say the operation completed successfully. Next type the command bootrec /fixboot, it should again say the operation completed successfully. Then type, bootrec /scanos and hit enter.
This command scans all your disks to see if there are windows installations on any of them. This could take some time depending on your system specifications and the size and number of disks to scan so you might have to wait a bit.
After scanning, it will inform you weather or not any windows installations are found on your disks, then go ahead and add it back to your boot list so the boot manager can locate it during startup. To do that, type the command, bootrec /rebuildbcd and hit enter and wait for the process to run.
After that it should tell you again that it has identified your windows installation, it then asks whether you want to add it to your boot list. Now if you have multiple windows installations it could give you all the available installations and the corresponding drives where they are stored.
So at this point if you would want to add all the installations to the boot list, then type A and hit enter to complete the process. Of course, A would also work if you have only a single windows installation. Now type exit to close the terminal, and then restart your computer to see if it now works. If that still doesn’t work, use the third approach.
METHOD THREE: Registry Backup (regback)
Here we will use the registry backup command called regback. This is a very powerful tool in windows, it mainly replaces your registry configuration with the last known good configuration you have on your PC, so basically changing your registry configuration to the configuration of your most recent successful boot up. To do that you will need to go back to this advanced options screen below.
Then click on the command prompt option. In the command line type the letter of the disk drive where you installed your operating system, usually is the drive c or in some cases it could be drive d if you have configured it so. Here type c: and hit enter. Next type dir, and hit enter.
Here if you find the folders Program Files and Program Files (x86), together with other folders like users, and Windows, then you’re in the right drive otherwise type some other drive latter e.g. d: and hit enter, then dir. Keep checking till you find the kind of folders and directories described above.
When you get to the right drive, first backup the current registry in case you have some need to restore it afterwards. For that you will type the command cd \windows\system32\config, and hit enter, then type MD backup and hit enter. Next type copy *.* backup, hit enter and wait a bit for the files to be copied.
After that, type in CD regback and hit enter. Then type dir once again, and here you should have a bunch of items with some 6, 7, or 9 digit numbers next to them.
NB: Is important that you have the kind of numbers described above. If you have zeros, then just exit this fix and move to the next fix. If you have valid numbers here, then go ahead and type the command copy *.* .. and hit enter.
Then type A hit enter. Next type exit and hit enter to complete the process. It should take you back to the page below where you can choose to continue to start up your computer or shut down.
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Please share your comments, questions and feedback in the comment section below.
The following video demonstrates the solutions in this tutorial.