Out of all the Blue Screen errors, the worst one, in my opinion, would be the one where your computer is not even able to boot properly. Because of this, even if you want to reinstall Windows, you cannot back up your important files. Hence, it would not be feasible to fix the system files and reinstalling usually talks a lot of time and resources. One such error is UNMOUNTABLE BOOT VOLUME BSOD on Windows 10. This Stop Error occurs if Windows if unable to access the volume containing the boot files.
Next, I recommended you create a System Restore Point. If you have one already, you can try restoring your computer from a System Restore Point. Or, if you do not have any habit to make a system restore point.
1. Check Hardware
If you get this message while updating to a higher version of Windows, check that you have compatible drivers for the disk controller and also re-check the drive cabling, and ensure that it is configured properly. If you’re reusing ATA-66 or ATA-100 drivers, make sure you have an 80-connector cable, and not the standard 40-connector IDE cable.
2. Use Automatic Repair
First of all, start by creating and booting from a bootable Windows 10 USB Stick.
When you are on the initial Windows Setup screen, click on Repair your computer on the bottom left corner.
Now, click on Troubleshoot. Then on the other screen, click on Startup Repair.
Now, select the operating system you want to repair.
It will now start to repair your operating system. Wait while the process is executed.
Read: Windows 10 will not boot up or start.
3. Fix the Master Boot Record
Master Boot Record or MBR is the location and architecture of the operating system installed. And if this architecture or location has tampered, it can cause multiple BSODs.
To carry on this fix, repeat steps in Method 1 until you click on Advanced Options.
Then select Command Prompt.
When the command prompt window opens, type in the following command,
Wait until the process is done and then Restart your computer for the changes to take effect.
4. Run CHKDSK
You can refer to the first part of this article about running the CHKDSK command in Command Prompt and try to fix your computer.
All the best!