How to fix broken Windows 10 bootloader ?

Broken Windows 10 bootloader is very easy to tell. Windows informs you that “An operating system wasn’t found” or “No bootable device found. Insert boot disk and press any key” after failing to boot. This usually happens after installing a second operating system, after trying to use free space of hidden disk partitions, formatting hidden partitions, experiments with EasyBCD, or just unexpected system failure. It does not really matter what cause the problem as it remains a problem. And it must be fixed. How to do that we will explain today.

Whether you have BIOS or UEFI, whether your Windows is on a GPT-disk with EFI bootloader or MBR-disk with a system reserved partition, all actions you need to perform will be almost the same for all scenarios.

Before we begin, we want to emphasize that errors such as we mentioned above are not necessarily caused by the corrupted bootloader. Inserted CD/DVD or connected USB flash drive, a new storage device or the malfunctioning old one may also cause that kind of errors to appear. So before doing any “fixing,” you should carefully retrace your steps before the error occurred the first time and maybe disconnect a problematic device or eject a CD/DVD.

Automatic bootloader repair

Windows 10 has many advanced recovery options that work pretty well, and most of the time it is enough to fix the problem (but it is not always the case). In order to repair the bootloader, follow the instructions below:

  1. Use bootable Windows 10 media or CD/ DVD with the same version of Windows you are currently using (64-bit or 32-bit) to boot.
  2. After doing that and selecting language, you will have an option to repair your computer. Click it.
  3. Click Troubleshoot in the next window that will appear, then – Advanced Options and select Startup Repair.

After Windows finishes repairs, two things may happen: you will see a message that will inform about the failed procedure, or your computer will be automatically rebooted (don’t forget to select proper boot priority in BIOS), and you will have your system restored. However, this method might not work, and you will have to do everything manually.

Repair bootloader using Command Prompt

For this method, you will need a bootable USB flash drive, Windows 10 CD/DVD, or Windows 10 recovery disc. If you have none of those, you will have to create one on another computer. For additional information on this topic, look for other related guides on our website.

Next step is to boot from the bootable media by altering boot sequence in BIOS (UEFI) or using Boot Menu. After booting, you will see a window asking you to select a language. You need to press Shift + F10 instead to open Command Prompt. If you are using a recovery disc, then go to the Troubleshoot menu, select Advanced Options, and click Command Prompt.

In the Command Prompt window you just need to enter three simple commands (one by one, pressing Enter after each):

  1. diskpart
  2. list volume
  3. exit

The “list volume” command will provide the information as you see in the screenshot above. Remember the letter of the volume with Windows 10 files (during recovery it might not always be partition C). In most cases, when you have just one operating system on your hard drive and hidden EFI or MBR partition, all you need to do to repair the bootloader is to execute the following command:

bcdboot c:\windows (instead of the letter “C” it might be another one as we mentioned above).

Remember: if you have several operating systems on your computer, for example, Windows 10 and Windows 8.1, you can execute the command bcdboot twice (first, you will have to select the directory with Windows files of the first system, and the second time – the directory with system files of the second operating system). The method does not work for Windows XP and Linux (Windows 7 – depends on configuration).

After executing the command, you will see a message saying that all have been created successfully. Now you can try to restart your computer normally (without a bootable USB flash drive or CD/DVD). Some system failures make booting longer as the system check HDD and SSD for errors after repairing the bootloader. You may get the “0xc0000001” error in the process – nothing to be afraid of as it can be cured with a simple system restart.

The second method to fix Windows 10 bootloader

If the first method did not work for you, go back to the Command Prompt menu as you did it before. Enter commands diskpart, then — list volume. Now pay attention to the partitions of the connected disks. Let’s take a new screenshot of the system with multiple volumes:

If you have a UEFI/GPT system, you will see a hidden volume with the FAT32 file system that has a size from 99 to 300MBs. If you have BIOS and MBR, you will see a hidden volume with the NTSF file system of 500MBs or less. You need to remember the number of that volume (volume 0, volume 1, and so on). You also need the letter of the partition where all Windows files are stored. Enter the following commands:

  1. select volume N
  2. format fs=fat32 OR format fs=ntfs (depending on the file system used).
  3. assign letter=Z (now this partition will be marked with the letter Z).
  4. exit (to close Diskpart)
  5. bcdboot C:\Windows /s Z: /f ALL (where C: — the disk with Windows files, Z: — the letter we have just assigned to the hidden partition).
  6. If you have multiple OS Windows installed on your PC, you need to repeat the command for the second copy (selecting another directory with Windows files).
  7. diskpart
  8. list volume
  9. select volume N (the number of the hidden volume we’ve assigned a new letter).
  10. remove letter=Z (delete the letter to make the volume indivisible in the system after reboot).
  11. exit

After completing all these steps, open Command Prompt and restart your computer normally in order to check how Windows boots. It should work ok now.

Conclusion

We hope this information was useful to you, dear reader. Unfortunately, not everything runs smoothly, and sometimes the problem just cannot be solved easily, which leaves you with one ultimate solution to fix all software Windows problems – reinstall the system.

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