Quick Summary
There are a few common reasons why you might see an “operating system not found” error when starting up your computer:
- Your hard drive is damaged or corrupted
- Boot files are missing or corrupted
- BIOS settings are incorrect
- Connection issues with the hard drive
This error indicates that your computer is unable to find or load the operating system files it needs to boot up. It’s often caused by hardware issues like a failed hard drive or loose cable connections. Software issues like corrupted system files or bootloader problems can also prevent your operating system from loading properly.
Diagnosing the exact cause typically requires some troubleshooting steps like checking connections, trying startup repair tools, accessing BIOS settings, or testing the hard drive. Repairing the issue may involve replacing hardware, reinstalling software, or tweaking BIOS configurations. Getting help from a repair technician is advisable if you’re unsure of how to fix it yourself.
What Does “Operating System Not Found” Mean?
The “operating system not found” error, also known as the “OS not found” or “no boot device found” error, means that your computer cannot find a bootable operating system when it tries to start up.
This is because during the boot process, the computer looks for system files like Windows or Linux in a specific location on the hard drive – usually a partition or directory containing the OS system files. When these critical files are corrupted, moved, or deleted, the computer receives the “OS not found” message instead of loading the operating system.
Some key points about this error:
- It prevents the computer from fully starting up into the desktop.
- An “OS not found” alert, black screen, or error message appears.
- The error indicates the OS boot files cannot be properly accessed or executed.
- It’s often due to hardware failure or software problems on the hard drive.
- Troubleshooting is required to identify and repair the specific cause.
In summary, this error means your PC is unable to locate the vital system files it needs to load the operating system and boot up your computer. You’ll need to troubleshoot the issue in order to get past the error and boot properly again.
What Causes the “Operating System Not Found” Error?
There are several potential causes for getting a “operating system not found” or “no boot device available” error when trying to start up your computer:
Hard Drive Issues
Problems with the hard drive are one of the most common reasons for this error. Specifically:
- Failing or corrupted hard drive – If the hard drive has bad sectors or other physical damage, it may prevent accessing the OS boot files.
- Disconnected or loose hard drive cable – A faulty cable connection can interrupt communication between the hard drive and the motherboard.
- Outdated hard drive controller drivers – Having incorrect or outdated controller drivers can sometimes cause boot issues.
- Accidental deletion of system partitions – This removes critical boot files needed for loading the OS.
Physically damaged, disconnected, or erased hard drives are a prime suspect for the “OS not found” problem.
Boot Configuration Issues
Errors related to startup settings and bootloaders can also cause this error:
- Corrupted master boot record (MBR) – The MBR contains info vital to initiating the boot process.
- Deleted or damaged system reserved partition – This 100MB partition contains boot files.
- Corrupted or misconfigured Boot Configuration Data (BCD) – The BCD directs the boot process.
- Invalid boot order in BIOS – An incorrect boot order can skip the system drive.
If the master boot record, boot partition, or BCD files get corrupted or reconfigured incorrectly, it can lead to the OS not loading properly on startup.
Software and Driver Issues
Software problems outside of the boot configuration can also cause trouble loading the operating system:
- Corrupted Windows system files – System file errors like in the registry or bootmanager can prevent startup.
- Virus infection – Some viruses target the MBR or boot files.
- Driver conflicts – Faulty or incompatible drivers blocking access to boot files.
- BCD editing mistakes – Manually editing the BCD can overwrite settings and cause boot problems.
Damaged system files, malware, buggy drivers, and mistaken BCD edits are examples of software-related issues that could result in the “OS not found” message appearing.
Hardware Incompatibility or Failure
Lastly, hardware compatibility or failure can lead to the error:
- Loose RAM modules – Improperly seated memory can cause boot freezing or failure.
- Failed hard drive PCB – If the hard drive PCB circuit board fails, it can block access to data.
- Incompatible storage device – Trying to boot from an incompatible storage device like a USB drive.
- Damaged or failing motherboard components – Issues on the motherboard itself can interfere with boot process.
Hardware components like RAM, the hard drive PCB, motherboard issues, or booting from an incompatible device are other potential causes to check.
How to Fix “Operating System Not Found” Error
Here are some steps to try fixing the “OS not found” error:
1. Check hardware connections
Make sure all internal cables and connections are firmly plugged in:
- Hard drive power and data cables
- RAM modules
- Motherboard power connectors
- SATA and power cables for optical or storage drives
Loose connections are a common cause of boot errors. Reseat connections firmly.
2. Inspect your hard drive
Check for signs of hard drive failure:
- Listen for clicking or beeping noises
- Use HDD monitoring software to check HDD health
- Perform a surface scan for bad sectors or data corruption
Replace the hard drive if it’s damaged or faulty.
3. Try booting from a recovery drive
A recovery drive or installation media may be able to repair the boot files:
- Insert the Windows or system restore disc and try to boot from it
- Use a recovery USB drive to access the Advanced Startup options
- Access automatic repair, system restore, or recovery environment
Run Startup Repair, System File Checker, or other recovery tools from the installation media.
4. Access the BIOS settings menu
Check for errors related to boot order or drive detection:
- Confirm the system drive with the OS is first in the boot order
- Enable CSM/legacy boot modes if UEFI fails
- Check that the hard drive is detected in BIOS
Correct any misconfigured boot, storage, or drive settings.
5. Rebuild the BCD
Use Bootrec commands to rebuild boot files:
- Bootrec /FixMbr – repairs the master boot record
- Bootrec /FixBoot – writes boot files to partition
- Bootrec /ScanOs – searches for installed operating systems
- Bootrec /RebuildBcd – rebuilds BCD
Run the Bootrec tool from a Command Prompt on the recovery drive to automatically rebuild and repair critical boot files.
6. Perform a system restore
Roll back your system to an earlier restore point:
- Boot from the recovery drive to access System Restore
- Choose a restore point from before the issue occurred
- Follow prompts to complete the system restore process
Restoring your system to an earlier state can often resolve software-related causes like driver issues or system file corruption.
7. Reinstall Windows completely
If other options do not resolve the issue, perform a clean install:
- Back up your data and reinstall Windows
- Delete existing partitions and recreate them during install
- Format the system drive before installing Windows
A fresh OS installation is most likely to fully resolve software-based causes and bad boot configurations.
Advanced Troubleshooting Tips
For difficult cases, try some of these advanced troubleshooting techniques:
- Boot to safe mode or safe mode with command prompt
- Run chkdsk, sfc /scannow, or DISM scan and repair commands
- Check Event Viewer for detailed error info
- Test hardware components like RAM, HDD, with alternate parts
- Update BIOS, chipset, SATA, etc. drivers
- Disable fast startup and CSM in UEFI BIOS
These additional steps may help uncover less obvious causes like driver conflicts, stranded system files, or failing hardware.
Preventing the Error in the Future
Some best practices to help avoid this error going forward:
- Keep your operating system, drivers, and software updated
- Install OS and boot updates as recommended
- Use an UPS to prevent unexpected power interruptions
- Don’t change boot configurations unless necessary
- Backup important data regularly
- Check HDD health and run disk error checks occasionally
Staying up-to-date, avoiding unnecessary boot changes, using backup power supplies, and monitoring your hard drive health can all help prevent this error in the future.
Recovering Data from a Drive with the Operating System Not Found
If you need to recover data from the inaccessible drive showing the error, you have a few options:
Boot to a Separate Drive
If you have another internal drive with an OS installed:
- Set first boot device to the working drive in BIOS
- Boot into the working OS
- Connect the unbootable drive as a secondary drive
- Copy data and files from the inaccessible drive
You may be able to access the file system by booting from a separate functioning drive instead.
Use a Bootable USB Drive
Or, boot from an external drive:
- Create a bootable USB drive with a live OS like Linux
- Change the boot order to the flash drive first
- Boot into the live OS environment
- Mount and copy data from the unbootable drive
Booting from removable media like a live Linux USB lets you access the drive as an external device.
Attach Drive to Another Computer
If available, hook up the drive externally:
- Use a hard drive enclosure or adapter cable
- Connect the unbootable drive to another working computer
- The drive should appear as an external storage device
- Copy desired data to the functioning computer
Attaching the hard drive externally via a USB enclosure, dock, or cable provides direct access to recover data.
Send to a Data Recovery Service
For significant recovery needs:
- Use a reputable data recovery company
- Specialized tools and clean room facilities
- Highest chance for recovering data
- But, very expensive fees in many cases
Professional data recovery firms may be able to fully restore data when other DIY options fail. But expect high costs.
Conclusion
The “operating system not found” is a common error that prevents your computer from loading Windows or other OS files on startup. It’s most often caused by hard drive issues, boot configuration problems, damaged system files, or hardware faults. Resolving it requires troubleshooting drive connections, boot settings, system files, and hardware. Recovering data may be possible by booting from other drives or sending to a recovery service. Avoiding unnecessary system changes, keeping updated backups, and monitoring hard drive health can help prevent this error in the future.