How to Fix UNMOUNTABLE_BOOT_VOLUME BSOD in Windows?

The Unmountable Boot Volume is a BSOD error that occurs when the boot volume is not accessible for the system. One of the main reasons that bring this Blue screen is a corrupted Master Boot Record (MBR). It is the first sector in the drive that provides information for system boot. If it gets corrupted, the system won’t boot, which will result in this error message.

Before jumping down to the solutions, make sure to restart your system. If the error persists, then proceed to follow the methods.

Note: Don’t skip any of the following methods because there are various different causes of this BSOD error.

1. Use Startup Repair

The first and basic solution is to use startup repair, which fixes certain problems and system files that are damaged or corrupted, preventing Windows from booting properly. To use a startup repair, you need to access the recovery options. To do so, follow the steps.

1. Turn off your system if it’s on.
2. Then press F9, F11, or F8 to start the automatic repair. You may have another key that takes you to the automatic repair screen. You can use other Function keys if the mentioned keys are not working for you.
3. Once the automatic repair fails to repair your Windows, it will show Shutdown and Advanced options. Click Advanced options to get into recovery options.
   
   
   If you still can’t access the Windows recovery environment, turn off your computer by holding the power button, then turn it back on. Repeat this process three times to get the startup repair. Now follow step 3 to get into recovery options.
4. Once done, click Troubleshoot > Advanced options > Startup Repair.
5. Wait for Windows to be repaired. Then, check whether the issue is fixed or not. If not, try other methods.

2. Repair Master Boot Record

Master Boot Record (MBR) is a sector in a disk that stores critical information about the OS that is used to boot the system. If this sector gets corrupted for some reason, such as internal problems in the disk or corrupted files, you won’t be able to boot Windows. In this case, you can try repairing the boot sector by following the steps.

1. Access the Advanced Options by using the first three steps of method 1.
2. Once you have access, click Troubleshoot > Advanced options > Command Prompt.
   
3. Wait for the computer to restart, then enter the following command one by one to repair the boot sector.

   bootrec /fixmbr
   bootrec /fixboot 
   bcdedit /export c:\bcdbackup
   attrib c:\boot\bcd -h -r -s
   ren c:\boot\bcd bcd.old
   bootrec /rebuildbcd

   

4. Once you have repaired the Master Boot Record, close the Command Prompt, and click Continue to see if the error is resolved or not.

3. Use a System Restore Utility

If you have a restore point created, then it could be the best way to fix this BSOD error. System Restore offers users to save the current state into a restore point. It is a troubleshooting utility that takes users to go back to their previous state if something bad happens.

If you don’t have created a restore point, still follow this method, as there are many Windows components and third-party optimization applications that create a restore point for the users.

To use a system restore utility:

1. Navigate to the Advanced Options by following the first 3 steps of method 1.
2. Now select Troubleshoot > Advanced Options > System Restore. Your system will restart to run the System Restore utility.
   
   
   If it says No restore points have been created on your computer, move on to the next method.
    
3. Click Next to run the utility, then select a restore point and again click Next.
   
4. Click Finish to restore your Windows.
   
5. Once done, now the issue should be fixed.

4. Run the CHKDSK Command

CHKDSK is a command-line utility that is used to fix bad factors in the disk. Your system disk may have corrupted sectors, preventing the system from booting. Therefore, try running the CHKDSK utility by following the steps.

1. Navigate to the Advanced Options by using the steps of 1st method.
2. Then select Troubleshoot > Advanced Options > Command Prompt.
   
3. Once the command prompt is opened, enter the following command and wait for it to execute.

   chkdsk /f d:

   Note: Replace D with a drive in which Windows is installed.

4. Once done, close the command prompt, and click Continue to see the result.

5. Reset Your System

If the error still persists, then the final option you are left with is resetting Windows. Resetting Windows will recreate all the system files into your OS drive, which will fix this issue.

Resetting Windows won’t delete data such as images and documents but will remove drivers, applications, along with corrupted system files.

However, if you are unable to reset your system due to an unmountable boot volume BSOD error, in this case, try reinstalling Windows. Refer to this article to reinstall Windows.

To reset your Windows, get into Advanced Options.

1. Select Troubleshoot > Reset this PC >Keep my files.
   
2. Then, select Local Reinstall.
3. Finally, click Reset to remove everything.
   
4. Once done, it should fix this error. 

6. Diagnose Your System Disk

According to the reports from affected users, they are unable to reset or reinstall Windows. If you are one of them, you may have a hardware problem in your system disk.

In this case, you will have to diagnose your system disk by removing the disk and connecting another one to install Windows. If you don’t have another disk, you can use the one that is already connected to your computer but make sure to backup the data first.