Unmountable Boot Volume error / BSOD – Fix
You are probably reading this article, because you have experienced, or are experience one of the dreaded Blue Screen of Death error messages – Unmountable_Boot_Volume. You might have tried other Windows startup options but your computer still gives this error in Safe Mode, or any other mode, causing quite some frustration.
Sometimes you might feel that the only option is to do a complete format & reload of your Windows operating system and possibly lose all your data. Luckily there is a way to potentially repair your computer without having to format, reload and lose your data.
With the steps provided in this article, I must mention that to attempt this fix, you should have a basic understanding of Command Prompt for Windows and the knowledge to create a bootable USB flash drive at least. Also, like any other fix out there, it is recommended that you make backups of your data (assuming you have made regular backups) as there might be a possibility that some of your data might become lost. I personally have not yet lost any client data with this fix, but rather be safe than sorry. Lastly, before we continue, I must just mention that there might be a possibility that this fix explained in this article might not resolve your current issue (as your HDD might be damaged and can not be fixed by software). So let us begin.
What you will need before you continue:
- Bootable USB flash drive with the install files of Windows 7 or Windows 10
- OR an original Windows 7 / 10 DVD (bootable)
- Some time on your hands
Steps to follow: (We will be using the Windows 7 screenshots for this article. The steps of the Windows 10 media is slightly different, but it comes down to the same result).
- Insert the Bootable media into your computer.
- Enter the BIOS, and make sure your SATA settings are set to either ATA/Legacy if it is on RAID or AHCI. You will need to change this back to the settings you had it on before you have put it on ATA/Legacy. If it is already set to ATA/Legacy, you can just ignore this step.
- Boot from the Windows USB flash drive / DVD. You might need to change your BIOS, or in stead of entering the BIOS, enter the boot options menu. The key to enter the boot menu at POST might differ from each desktop / motherboard manufacturer. Make sure you select the correct device to boot from the USB / DVD.
- When the Windows pre-install files have loaded, you will be prompted to select your language and keyboard layout. Make your selection and click the Next button.
- Now, click on “Repair your computer”
- When you have clicked on “Repair your computer”, a new Window should pop up and you then need to select the “Command Prompt” feature. Again, the steps for Windows 10 will be different, and at the end you will also need to have the Command Prompt window open.
- Once Command Prompt is open, you will need to determine what volume is your primary hard drive partition as well as the System Reserved partition. You can make use of DiskPart to determine the volume which you will need to repair, but for the sake of keeping this article simple, we will not make use of DiskPart, as it might be destructive when not used correctly. You might find that C: might point the USB / DVD media which you have booted from. For the next step you might need to determine what drive letter is your System Reserved partition and what is your primary partition.
- Still in Command Prompt, type start from “A:” then go to “B:” and so forth to determine what drives are the System Reserved & primary partitions. PLEASE NOTE: Some instances might not show you the System Reserved partition, so just ignore that and carry on to find the drive letter of your primary partition. ALSO: When a specific drive letter takes too long to show you the directory contents of the drive, it is also possible that it is the drive letter you will need to perform the following steps of the repair. Write it down (or just remember the drive letters) which you will use in the next steps.
- To make sure you have chosen the correct drive letter, make use of the “dir” command to list the files on the drive. You will find your personal files when you browsed to your “user” folder in Command Prompt. Again, you need to have some knowledge on how to navigate between folders when using Command Prompt (“cd\users”).
- When you have determined the drive letter(s) of both the System Reserved partition and primary partition (or the only partition you can find to perform the fix), you will need to navigate away from that drive. For example, if the partition which the fix need to be applied to is E: then you need to go to any other available drive / partition which does not form part of the drive which will need to be repaired (for example C:). If this sounds confusing, just remember that C: would most likely be the bootable USB/DVD which you have inserted for the purpose of this article’s repair steps.
- Now type the following (assuming E: is the drive which need to be scanned) without the quotation marks:
- “chkdsk e: /f /x /r” and press Enter.
- If it prompts you to press a key to continue, follow the steps so that chkdsk can continue with the scan.
- PLEASE NOTE: This scan might take a couple of hours to complete. This is a 5-stage scan / repair process and should not be interrupted at any time.
- Just to delve into some technical details of the command used above:
- chkdsk is a built-in Windows Command Prompt application version similar to ScanDisk which scans the drive(s) for errors, bad sectors, etc.
- d: points to the drive / partition which need to be scanned.
- /f parameter will tell chkdsk to fix errors on the disk (where physical data is located on the drive).
- /x parameter forces the volume to dismount first (if needed).
- /r parameter locates bad sectors and recovers readable information on the volume which will be scanned.
- You might need to follow steps 9.1 again on the System Reserved partition (usually a hidden partition of about 100MB in size, not visible in Windows Explorer) of your drive (if it is available on command prompt) as well for this fix to work – “chkdsk d: /f /x /r” and press Enter.
- You will notice that during the scan, the log displayed might show some files which will be moved to readable areas of the drive, or bad sectors marked, etc. Just let it continue until the total progress is 100% completed.
- When the scan is completed and you have reviewed the scan log, you can now restart your computer. Do note that if you have changed the boot options in your BIOS earlier, that you must now change it back to boot from your built-in hard disk drive. ALSO, if you have changed the SATA mode (as explained in Step 2), you need to change it back to the state it was set before you have changed it (to AHCI or RAID). This is an important step, as your PC might not boot to Windows correctly of you forget to set your SATA mode to where it was previously.
- Windows should now boot. If it prompts you to select either “startup repair” or “boot Windows normally” make sure you select to boot Windows normally.
- If you Windows booted up, but prompts you to continue to check the disk for errors, do NOT press anything – let Windows complete the scan and fix what need to be fixed. This should not take too long to complete though.
- If the PC prompts to restart, let it restart by itself (unless it prompts you to manually restart the PC, which you should do), then it should boot to Windows without giving you the Blue Screen of Death.
I just feel I should mention again that this fix might not always work as desired, as sometimes the utilities used might be unable to repair the problems experienced. In my experience, I have had quite some success with the chkdsk fixes on numerous BSOD errors throughout the years, and this is the safest solution to follow, as well as something to try first before you need to format & reload your HDD. This is obviously a very tedious process to follow as it will take quite some time, therefore patience is key. I would also not recommend you attempt this fix if you are not familiar with tools & steps used throughout this article. You will need to have an understanding on how hard disk volumes & partitions work for this article to make any sense, as well as have some knowledge on Command Prompt commands to successfully execute the steps in this article.
I truly hope that this article was of great value to you, and if you want to add your comments or suggestions regarding this article, please feel free to comment below.