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Fixed: Unmountable Boot Volume Error in Windows 10/8/7

Position: How Tos - Disk Utilities - Fixed: Unmountable Boot Volume Error in Windows 10/8/7

Summary
Do you encounter the unmountable boot volume Windows stop error when you are trying to boot Windows 10/8/7? This error is painful, for it prevents you from getting into Windows. Fortunately, it is possible to get it fixed with proper solutions. This article will provide several solutions to fix the blue screen unmountable boot volume error and help you get back into your PC. If data recovery is needed, you can download DiskGenius to search for lost data.
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Table of Contents



Unmountable boot volume error description

When the error appears, your computer cannot load Windows properly and gives a blue screen of death or a stop code with following error message:

Unmountable boot volume

Your PC ran into a problem and needs to restart.
We'll restart for you.
If you'd like know more, you can search online later for this error: UNMOUNTABLE_BOOT_VOLUME

This error can appear in different situations, for example, you may receive the error during Windows Installation Setup, Windows Setup or some important work. The boot volume here presents the partition of your hard drive that installs Windows system. The volume may get corrupted or damaged due to various causes and thus turns to unmountable. Amongst all of the blue screen errors, the UNMOUNTABLE_BOOT_VOLUME error might be the worst one, for users cannot even boot properly. It becomes hard to fix the issue when we cannot access Windows. Moreover, if you choose to reinstall operating system, you will have to spend much time and efforts. Fortunately, there are workable solutions that can be tried even if you do not have a Windows installation CD/DVD.


What causes the unmountable boot volume error?

The blue screen error unmountable boot volume indicates that Windows fails to mount the boot filesystem. It is not common to encounter such error and many factors can lead to the issue.

  • Corrupted boot volume: system partition and other system-related partition holds files that are important to Windows booting, and these partitions may fail to work due to corrupted MBR (Master Boot Record), damaged RAM, improper BIOS settings, etc.
  • The booting process tries to load Windows from incorrect volume: When the bootloader (NTLDR or BOOTMGR) starts to load system according to the configuration file, it passes along information to kernel and telling where OS can be loaded. It happens that the configuration file is not correctly set or refers to wrong volume, the boot process won't be able to load Windows correctly.
  • Windows partition gets deleted or changed. If system volume gets removed or changed from hard drive prior to booting to Windows, you will receive UNMOUNTABLE_BOOT_VOLUME blue screen error.
  • Hard disk bad sectors: Bad sectors prevent normal read/write actions, cause data loss, partition loss and other issue. If the boot volume contains bad sectors, Windows will not be able to boot as usually.

Reasons behind the blue screen error can be extended, for there might be other causes. No matter what the cause, we need to fix it in order to make computer work again. If you want to try fixing the error on your own, you can take a while to try following guides.


How to fix unmountable boot volume error in Windows 10?

When you encounter the blue screen of death error, you don't have to be anxious that much if the error only appears one time. Once in a while, Windows just runs into an error temporarily and the error won't happen again. If you come across the unmountable boot volume problem, you can try restarting your PC and check if you can boot to Windows. If the error keeps appearing after rebooting several times, you need to proceed with some troubleshooting.

First thing first, the error to be fixed prevents you from accessing Windows on your PC, and you need to get a installation CD or bootable USB drive before trying following solutions. If you do not have one, you can create a WinPE-based bootable USB disk with DiskGenius Free Edition: Tools > Create WinPE bootable USB drive of DiskGenius.

Unmountable boot volume

Click OK button and wait for several seconds to create the bootable USB disk.

Unmountable boot volume

Once the bootable USB drive is successfully created, you can insert it to your computer that cannot boot and enter BIOS to change boot order. Save changes and restart computer, and your PC will boot from the USB drive. If you have no idea on how to modify boot sequence in BIOS, you can contact technical support of your computer or motherboard' manufacturer.

Solution 1: Run an SFC scan to fix corrupted system files

SFC (System File Checker) is an important utility that can search for and repair corrupted Windows system files. Since boot volume cannot be mounted, there might be something wrong with it. Thus, it is worth a try to run SFC in the first place.

Step 1   Launch Command Prompt.

Boot your PC from the bootable USB disk, and click Start menu to choose Windows Command Processor.

Unmountable boot volume

Step 2   Type command sfc /scannow and hit Enter key.

Wait for the scanning to complete and it will show you if any errors are fixed. Then reboot computer and see if it is able to load into Windows.

Unmountable boot volume

Solution 2: Perform a chkdsk

Step 1   Open Command Prompt on your computer after it is booted from the bootable USB disk.

Step 2   Type in command chkdsk /r c and press Enter key.

Unmountable boot volume

Note:

  • The letter C here refers to the boot volume on this computer and you need to replace it with correct letter in case the boot partition uses other drive letter.
  • Type Y and press Enter key if you see the message "Chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)"
  • It may take a while to complete disk checking, and you need to be patient to wait a bit. When it is done, restart computer and check if the problem is fixed.

Solution 3: Fix Master Boot Record

MBR (Master Boot Record) saves information regarding where operating system is installed on your hard disk and helps it load properly during booting process. If MBR gets corrupted, system cannot boot correctly. Let's check out how to fix corrupted MBR.

Step 1   Launch DiskGenius.

Insert the bootable USB disk to the unbootable computer and boot from the disk, after which DiskGenius WinPE Edition will be launched automatically.

Step 2   Select the hard drive that needs fix MBR and choose Disk > Rebuild Master Boot Record, as follows:

Unmountable boot volume

Click Yes to confirm the action and DiskGenius will rebuild MBR at once.

Unmountable boot volume

Solution 4: Check & repair bad sectors

Sometimes computer may turn to quite slow or even stop responding when you access certain files. Such issue happens when your hard drive contains bad sectors. Besides, bad sector can also corrupt partition, cause data loss, partition missing, etc. How to check and repair bad sectors?

Step 1   Launch DiskGenius WinPE edition after your PC boot from the bootable USB. Select the hard drive where Windows is installed, and click Disk > Verify Or Repair Bad Sectors, as below:

Unmountable boot volume

Step 2   Click Start Verify button and DiskGenius will start to scan the disk and test if there are any bad sectors.

Unmountable boot volume

If the disk indeed has bad sectors, you can click Repair button to try repairing bad sectors. Please note that repairing bad sectors may cause data loss, please back up important file in advance.


How to recover data from unmountable boot volume?

It is frustrating to find that important files are lost after getting the UNMOUNTABLE_BOOT_VOLUME error. Don't worry! Lost files can be recovered from unmountable boot volume or unbootable PC using professional data recovery software. DiskGenius is reliable and effective tool to recover data lost due to system crash, deletion, formatting, RAW drive, partition missing, disk damage, etc. It supports to create bootable USB disk, which makes it easy to recover data when system cannot boot. This recovery software works on various devices, including hard disk, external disk, USB flash drive, memory card, pen stick, virtual disk, RAID, encrypted drive, etc. Here is a complete guide to quickly recover lost files with DiskGenius.

Step 1   Install DiskGenius on your computer and launch it after installation.

If your computer cannot boot to Windows, you can create bootable disk using DiskGenius and launch DiskGenius WinPE edition. We've talked about how to create a bootable USB disk in previous part and we will not repeat the process here.

Step 2   Now choose the location of lost files and click File Recovery button from toolbar.

File recovery can be used to recover deleted files, retrieve lost files from formatted, corrupted, RAW, inaccessible and damaged partition, and restore files from unallocated disk space. If the partition gets lost due to partition deletion, disk formatting, repartitioning, reset factory, etc. you can try Partition Recovery.

Unmountable boot volume

Step 3   Scan the volume.

Select recovery options according to your data loss reason and click Start button. Then DiskGenius starts to scan the volume to look for lost files and folders.

Unmountable boot volume

Step 4   Preview recoverable files.

You can double click a file to preview it in the previewing window, which helps to make sure if it is the real file you want to restore.

Unmountable boot volume

Step 5   Recover files from the unmountable boot partition.

Now choose files and folders you want to recover, right-click on selected data and click Copy To. Then you can set a location to save recovered data.

Unmountable boot volume
Conclusion

Now you must have become able to solve the unmountable boot volume error in Windows 10/8/7 on HP, Dell, Lenovo and Toshiba computers. You can try these solutions to get rid of the blue screen problem and successfully boot to Windows again. DiskGenius is versatile tool that can help recover data, backup system, test hard disk, create bootable disk, etc. and it is recommended to install the software on your computer to improve performance and safeguard data. Again, if you have better solutions to fix the error, please share it with us; if you need any help or question regarding the topic, please feel free to contacting us.

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