Get the fix for “Operating System not found” boot error for Windows XP, Vista, 7, 8 or 8.1.

This error is also very common for Sony VIO laptops, including T-Series ultra books and S-Series.

Below are all available solutions you can do to repair this error. If none of these solutions are working for you, you can download Easy Recovery Essentials repair disk for Windows that is guaranteed to fix this error.

Alternative error messages. Another common message is “Missing operating system”.

Operating system not found, Windows error

The “Operating system not found” error

Why your PC shows Operating System not found

A faulty hard disk can be the cause for this error, but before you replace it go through the fixes detailed below as simple solutions, such as rebuild the BCD or running Automatic Repair from your Windows installation disc, can solve it faster and you may still be able to keep your important data.

A corrupt master boot record is another cause, which can be fixed by rebuilding the BCD.

Guaranteed Fix: Use Easy Recovery Essentials

Easy Recovery Essentials is guaranteed to fix the “Operating System not found” error automatically using its built-in Automated Repair option. EasyRE is currently available for Windows XP, Vista, 7 and 8 and can be downloaded and created on any PC.

  1. Download Easy Recovery Essentials. Make sure to note your Windows version (XP, Vista, 7 or 8) before you download EasyRE. This guide can help you identify what version of Windows you have installed.
  2. Burn the image. Follow these instructions on how to burn the bootable ISO image very carefully, as making a bootable CD can be tricky! Alternatively, these instructions explain how to create a bootable EasyRE recovery USB stick/drive.
  3. Boot up your PC from the Easy Recovery Essentials CD or USB you created.
  4. Once EasyRE is running, choose the “Automated Repair” option and click Continue.
    EasyRE Home

    Choose “Automated Repair” in Easy Recovery Essentials

  5. After EasyRE scans your computer’s drives, identify and select the drive letter for your Windows installation from the list, and then click on the Automated Repair button to begin.
    EasyRE displays a list of found Windows operating systems

    Choose the drive associated with the Windows installation you’re trying to repair.

  6. Easy Recovery Essentials will start analyzing the selected drive for problems. EasyRE will test for and attempt to automatically correct errors with the disk, partition, bootsector, filesystem, bootloader, and registry. No intervention is required, as EasyRE’s repair is fully automated:
    EasyRE: Automated Repair

    Easy Recovery Essentials searches for errors and makes corrections to the selected Windows installation.

  7. Once the process is complete, EasyRE will report its findings. Click on the Restart button to reboot your PC and test the changes.
  8. The “Operating System not found” error should now be fixed as your PC begins to load:
    EasyRE: Automated Repair

    Windows, booting up successfully.

You can download Easy Recovery Essentials from here.

Fix Operating System not found or Missing

Windows Setup CD/DVD Required!
Some of the solutions below require the use of the Microsoft Windows setup CD or DVD. If your PC did not come with a Windows installation disc or if you no longer have your Windows setup media, you can use Easy Recovery Essentials for Windows instead. EasyRE will automatically find and fix many problems, and can also be used to solve this problem with the directions below.

Fix #1: Verify your hard drive status in BIOS

Verify that your hard drive appears in your BIOS settings. If it doesn’t appear, make sure all the cables of the hard disk are connected properly.

A faulty hard disk or IDE cable can lead to this error. Consider replacing the hard disk or the IDE cable. You can test it by connecting your hard disk to another computer and see if it’s working properly afterwards.

If you happen to have a faulty hard disk, it’s important to save your important data (family pictures, favorite movies, job related files etc) before replacing it or trying to save as much as possible.

Download Easy Recovery Essentials that lets you access your data even if your PC displays “Operating System Missing”.

Fix #2: Rebuild the BCD using bootrec.exe

Just as with the BOOTMGR is Missing“error, rebuilding your computer’s BCD can fix boot loading issues. In this case, the “Missing Operating System” error.

Your need your Windows installation disc to access bootrec.exe, a tool built in Windows Recovery Environment (Windows RE).

The bootrec tool is only available for Windows Vista, 7, 8 or 8.1 systems. Windows XP systems uses the bootcfg tool instead.

Here are the steps to access bootrec.exe:

  1. Insert your Windows install disc
  2. Press any key at the “Press any key to boot from CD or DVD” message
  3. Choose Repair your computer after you select the language, time and keyboard method
  4. Select your Windows installation drive (usually C:\) and click Next
  5. Select Command Prompt in the System Recovery Options box
  6. Write the following commands in the Command Prompt:
    bootrec /fixmbr
    bootrec /fixboot
    bootrec /rebuildbcd
  7. Press Enter after each command

Fix #3: Run Automatic Repair

Windows Vista, 7, 8 or 8.1 installation discs have an Automatic Repair application that you can run and use to fix this error.

Here are the steps to access Automatic Repair:

  1. Insert the original Windows Vista, 7, 8 or 8.1 disc
  2. Restart your computer and boot from the disc
  3. Click Next in the Windows setup page after you select: Language to install, Time and currency format and Keyboard or input method
  4. Click Repair your computer
  5. Click Troubleshoot
  6. Click Advanced options
  7. Select Automatic Repair and select your operating system
  8. Wait for the process to finish

Operating System not found on Sony VAIO Laptops

The eSupport section of Sony.com suggests the following solutions if your VAIO laptop is showing this error:

  1. Remove all removable media, e.g. USB flash drives, CDs, DVDs etc.
  2. Reset BIOS settings back to default

Here are the steps to reset VAIO’s BIOS settings if you have Windows XP, Vista, 8 or 8.1:

  1. Remove any peripheral devices you may have connected to the laptop
  2. Restart the computer and press the F2 key when the VAIO logo appears
  3. When the BIOS setup screen appears, press the right arrow key (->) to select the Exit menu section
  4. Select Get Default Values by pressing the down arrow key
  5. Press Enter at “Load Optimized Defaults”
  6. In the Load Optimized Defaults make use of the arrow key to select Yes and then press Enter
  7. Again use the arrow keys to select Exit (Save Configuration) and press Enter

Here are the steps to reset VAIO’s BIOS settings if you have Windows 7:

  1. Press and hold the Assist button after you restarted the laptop until the VAIO black screen appears on the monitor
  2. When the VAIO Care Rescue Mode screen appears use the arrow keys to select Start BIOS setup [F2] and press Enter
  3. Press the F9 key to reset the VAIO’s BIOS to the original default values

In BIOS, make use of the arrow keys to navigate through the screens and options, Enter key to select an option and the ESC key to exit the active window.

More Information

Linked Entries

Support Links

Applicable Systems

This Windows-related knowledgebase article applies to the following operating systems:

  • Windows XP (all editions)
  • Windows Vista (all editions)
  • Windows 7 (all editions)
  • Windows 8 (all editions)
  • Windows 8.1 (all editions)