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Learn how to quickly fix the "UNMOUNTABLE BOOT VOLUME" error on Windows computers and recover important data without entering the system. Expert solutions provided in this article.



When an “UNMOUNTABLE BOOT VOLUME” error message appears, it means that the user cannot load the operating system and access data on the computer. The boot volume is where the main boot files and the Windows operating system are located. It is one of the important partitions in the computer hard disk. Therefore, if there is a problem with the boot volume, it will affect the normal startup of the computer.
The “UNMOUNTABLE BOOT VOLUME” blue screen error can occur for several reasons:
● System files are damaged.
● The system hard disk is faulty.
● The computer hardware connection is loose
● A problem occurred during the Windows 10 update.
Now that we understand the approximate cause of the “UNMOUNTABLE BOOT VOLUME” blue screen error, we can start fixing the problem. If you do not need to transfer important data from the computer, you can directly jump to the third part of this article to see the repair method. If your Windows computer contains important files and you don’t want to lose any files due to repair operations, you can check the method in the second part to transfer, backup or restore important data without entering the Windows system.

II. Use Renee PassNow to transfer or recover data before repairing

1. What is Renee PassNow?

Renee PassNow is a professional system rescue software, which can help Windows users clear Windows account passwords, create new administrator accounts; restore disk/memory card data, recover data after hard disk formatting; transfer disk files; erase or scan Disk files, etc. In addition, this software also supports repairing Windows system problems, such as: repairing MBR boot records, DBR error parameters, 0xc00000e, Windows system startup failure, and some problems that cause black screen or blue screen, etc. As a system rescue tool with various functions, it is perfectly compatible with multiple systems including Windows 10/8.1/8/7/XP/Vista, and can meet the system rescue needs of different users.
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2. How to use Renee PassNow to transfer or recover data?

When the Windows system has a blue screen and cannot be started, you can create a startup disk through Renee PassNow, then start the computer through the startup disk, and then use the functions provided by the software to transfer or restore files. Specific steps are as follows:
Step 1: Download and install Renee PassNow on other computers that can log in and run normally, then connect the U disk to the PC, run Renee PassNow, and then check in “Step 1: Select creation method” (Create a Live USB) option. (Note: Before performing this operation, please make sure that the important files in the U disk have been saved in other locations, because the operation process will delete all the data in the U disk.)
Step 2: Next, select (x64) or (x86) according to the system type, click the (Download Now) button to download the ISO file, click the (Create a Live USB) button after the file is downloaded, and click the (Eject USB) button.
use renee passnow to create usb to reset passnword
Step 3: Connect the created boot device to the computer that needs to transfer data, turn on the computer, and then the shortcut key to enter the BIOS will be displayed on the computer screen (the display time of this interface is very short, maybe only one or two seconds), click continuously BIOS shortcut key to enter the BIOS setting interface, and then set the boot U disk as the first in the boot sequence in Boot Priority, then save the settings and restart the computer.
select boot order
Step 4: Wait for a while, after Renee PassNow is loaded, select (Data Transfer). If you need to transfer the data of the entire hard disk, you can select the (Data Backup) option.
Windows 10 recovery drive select data transfer function in Renee Passnow to sovle windows 10 won't boot from USB
Step 5: You can click on each disk drive letter (C/D/E/F, etc.) to check whether important files are lost. If not, it is recommended that you transfer them to an external disk. The operation of transferring data is very simple. For example, if you want to transfer the data in the C drive to the G drive, you can first select the C drive on the upper left, select the G drive on the upper right, and then select the files in the C drive, and click the Copy function button in the middle. Disk data can be easily transferred. If there is a file you want to delete, you can also click the (Delete) button in the middle after selecting the file, but the deletion operation cannot be undone, please operate with caution.
data transfer in Renee Passnow
Step 6: If you find that there is data loss, please select the (Undeleter) option on the main interface of the function, and click the (Run) button.
data recovery function in Renee Passnow
Step 7: Select (Fast Partition Scan) to scan the target hard disk.
show undeleter functions through passnow
Step 8: After the scan is complete, select the file to be recovered, click the (Recover) button to execute the data recovery command, please save the file in another external disk, eject the U disk after the recovery is complete, and then perform other operations on the computer, such as maintenance , replace the hard disk or reinstall the system, etc.


1. Restart the computer

When the blue screen prompts “Stop code: UNMOUNTABLE BOOT VOLUME”, the error interface will prompt your PC to encounter a problem and need to restart. At this time, you can follow the suggestions on the interface to restart the computer. Because Windows 10, like any other operating system, can experience temporary issues that are detected and automatically fixed the next time the user starts the computer. If you still have a blue screen and the same prompt after restarting, you can continue to check the following repair methods.

2. Perform startup repair

You can also try to fix the UNMOUNTABLE BOOT VOLUME error through the Startup Repair function in the Windows recovery environment. Windows Startup Repair fixes problems that prevent Windows from loading and replaces missing or damaged files. Here are the detailed steps to perform a startup repair:
Step 1: Insert the Windows installation disk (DVD or U disk) into the computer, and press F2 or F10 or DEL or ESC keys continuously (there may be slight differences due to different computer brands) to enter the BIOS setting interface when starting up, and install the disk Set first in the boot order. Boot the computer from the Windows installation disk and click the option Repair Your Computer to enter the recovery environment.
Repair your computer
Step 2: After entering the recovery environment, select Troubleshooting > Advanced Options > Command Prompt. After waiting for Windows Startup Repair to complete, restart the computer to see if the problem is resolved.
command prompt

3. Use the Bootrec command to repair the master boot record

When a Windows boot problem occurs, you can use the Bootrec command to repair a damaged master boot record (MBR) or boot configuration data file. This method needs to enter the recovery environment and then operate. Proceed as follows:
Step 1: Press the power button to turn it on, and turn it off before the startup logo appears. Repeat this step three times to enter the Windows recovery environment. Or use the Windows installation disk to start the computer, you need to enter the BIOS menu through shortcut keys (such as DEL/ESC/F2, etc.), set the Windows installation disk as the boot preference, then save the settings and restart the computer, in the Windows installer Install Now interface, select the Repair Your Computer option to enter the recovery environment. (Click here to learn how to make a Windows installation disk)
Repair your computer
Step 2: After entering the recovery environment, select Troubleshooting > Advanced Options > Command Prompt.
command prompt
Step 3: In Command Prompt, enter the following command. Each time you enter a command, you need to press the key Enter. After the repair is complete, restart the computer to see if the problem is resolved. If you want to know the specific meaning of the following commands, you can click on the Microsoft official guide page to learn.
bootrec.exe /fixmbr
bootrec.exe /fixboot
bootrec.exe /scanos
bootrec.exe /rebuildbcd

4. Run the chkdsk command to check for system disk errors

The full name of chkdsk is Microsoft Check Disk, which is an instruction program for disk checking. Its basic function is to scan the integrity of the file system on the disk and repair the errors of the file system; it also supports scanning the sectors on the disk and trying to repair bad sectors. Proceed as follows:
Step 1: Repeat Step 1 and Step 2 in Method 3 to open a command prompt in the Windows recovery environment.
Step 2: In the opened command prompt window, enter chkdsk C: /f /r /x (C refers to the disk number of the system hard disk, which can be changed according to the actual situation, /f will try to repair the errors found on the disk, /x means to force unmount the drive before starting the scan; /r means to scan for and try to repair bad sectors), and press Enter to fix errors.
Enter chkdsk C: /f /r /x
Step 3: If you are prompted that chkdsk cannot be run because the target disk is in use, whether to perform the check task the next time you restart the computer, please press Y to agree to run the chkdsk check when the computer restarts next time. After the chkdsk check is complete, restart the computer to see if the problem is resolved.

5. Run the SFC command to check system file errors

SFC (System File Checker) is a utility in Windows that scans all protected system files, checks the integrity of system files, and replaces abnormal, damaged files with the correct versions of Microsoft programs. or missing versions. Specific steps are as follows:
Step 1: When your computer won’t start, you can run SFC command with the help of Command Prompt in Windows Recovery Environment. Please perform step 1 and step 2 of method 3 to open the command prompt in the recovery environment.
Step 2: In the opened command prompt window, enter the command SFC /scannow and press the key Enter. Next, System File Checker will perform a system scan and fix problematic system files. After the repair is complete, restart the computer to see if the problem is resolved.
Type SFC /scannow

6. Check the computer hardware connection

If you have tried the above several repair methods, but still cannot solve the problem, then we can also check the connection status of each hardware of the computer to see if the connection is tight. Especially the hard disk where the operating system is located, if the hard disk is loosely connected to the motherboard, it may fail to start. Tips: Checking the hardware connection status should be done when the computer is turned off and disconnected from the power supply.
The above are the common methods to solve the UNMOUNTABLE BOOT VOLUME error. If you still cannot enter the Windows system, it is recommended to try to reinstall the system. Before reinstalling the system, you can transfer or restore important files in the device with the help of a professional system rescue tool – Renee PassNow, follow the second part of this article.