Having an inaccessible boot device can be frustrating. When you turn on your computer and see an error message saying that the boot device is inaccessible, it means the operating system cannot find the drive or location that contains the files needed to start up the computer.
There are several potential causes for a boot device being inaccessible. By understanding the most common reasons this can occur, you can troubleshoot the issue and get your computer booting properly again.
Common Causes of an Inaccessible Boot Device
Here are some of the most common culprits that can lead to the “boot device inaccessible” error message:
- Hard drive failure or corruption
- Incorrect boot order in BIOS
- Disconnected hard drive
- Damaged hard drive cable
- Outdated BIOS/firmware
- Damaged boot loader
- Virus or malware infection
Let’s explore each of these common causes in more detail.
Hard Drive Failure or Corruption
One of the most common reasons for the boot device being inaccessible is some type of problem with the hard drive itself. This could include physical damage to the drive, corruption of system files, or failure of the hard drive.
Hard drives can develop bad sectors or mechanical problems over time that prevent them from being read properly by the computer. The boot files may become corrupted from an unexpected shutdown, power outage, or virus infection. File system errors can also make the drive unreadable.
If the hard drive has completely failed and is making mechanical clicking or beeping noises, it likely needs to be replaced. More minor corruption issues can sometimes be repaired with disk utilities that check and repair file system errors.
Incorrect Boot Order in BIOS
The BIOS controls the boot order of storage devices connected to your computer. If the hard drive with your operating system and boot files is not first in the boot order, the computer will not be able to load the OS at startup.
Check your BIOS settings to make sure the hard drive or SSD with your Windows, MacOS, or Linux installation is listed first in the boot sequence. If another storage device like a USB drive is set as the first boot device, change this so the correct hard drive is prioritized.
Disconnected Hard Drive
It may sound obvious, but sometimes the hard drive can become physically disconnected from the computer. This could happen due to a cable coming loose, a damaged connector, or a drive that is not fully seated in the bay.
Open up your computer case and check that all the cables are firmly plugged into the hard drive and motherboard. If it is a SATA drive, make sure the power cable and data cable are both properly connected. Also check that the drive is snugly fitted in the drive bay.
Damaged Hard Drive Cable
Even if the hard drive itself is perfectly healthy, a damaged cable can prevent the computer from being able to access the boot files on the drive.
Cables can become crimped or worn over time. Try swapping out the hard drive cable with a known good cable to see if that resolves the booting issue. This is an affordable troubleshooting step that could potentially fix the problem.
Outdated BIOS/Firmware
If you have recently changed hardware in your computer, an outdated BIOS or firmware could cause compatibility issues leading to the boot device not being found.
Check for updated firmware or BIOS from your motherboard manufacturer and install the latest version. This helps ensure optimal compatibility with your specific hardware configuration.
Damaged Boot Loader
The boot loader is software that loads the operating system kernel and essential drivers needed to start the OS. If this boot loader file becomes corrupted or damaged, it can result in the boot device not being accessible.
On Windows computers, you may be able to repair the boot loader using the automatic Startup Repair feature. Otherwise, you may need to reinstall the boot loader manually from an OS installation disc or repair tool.
Virus or Malware Infection
Viruses and malware sometimes target and modify critical boot files in order to infect a computer. This kind of infection can damage boot loaders, Master Boot Records, or other vital files required for booting.
Use antivirus software to scan for and remove infections. You may need to also repair or replace damaged system files from a clean OS installer disc.
How to Troubleshoot an Inaccessible Boot Device
When you see the “boot device inaccessible” error, there are a number of troubleshooting steps you can take to identify the cause and fix the problem:
- Check BIOS settings – Make sure the boot order lists the correct hard drive first.
- Inspect hardware connections – Check cables and make sure the hard drive is properly connected and powered on.
- Test with another hard drive cable – Swap cables to rule out a damaged interface.
- Try booting from an OS recovery disk – This helps determine if the hard drive is detected and accessible.
- Boot into Safe Mode – Getting into Safe Mode can allow you to troubleshoot software issues.
- Run disk repair utilities – Check and repair file system errors and bad sectors.
- Reseat the hard drive – Remove and firmly reinstall the drive to make a better connection.
- Update BIOS/firmware – Get the latest firmware code to improve hardware compatibility.
- Use antivirus tools – Scan for and remove any infections that may have damaged boot files.
- Reinstall or replace hard drive – If drive cannot be repaired, it may need to be wiped and reloaded or swapped out.
Taking methodical steps to diagnose why the boot device is not being found can help identify whether it is a hardware, connectivity, software, or OS issue. Complex problems may require taking the computer to a repair technician if you exhaust all home troubleshooting options.
Repairing a Damaged Boot Device
If you determine the hard drive itself has physical damage, corruption, or file system errors, it may be repairable without requiring a full replacement.
For minor file corruption, try running CHKDSK in Windows or fsck on Linux to check and fix basic file system problems. If the drive can still be detected, disk utility software may be able to repair more advanced issues like bad sectors.
Tools like SpinRite can deeply analyze hard drives and recover data from corrupted drives. Software can assist with repairing the Master Boot Record if it becomes damaged.
If the physical drive motor, head, or internals have failed, however, this typically requires a drive replacement or professional data recovery service. Staying on top of hard drive health with regular scans using utilities like S.M.A.R.T. can help avoid catastrophic failures.
Replacing a Non-functional Boot Hard Drive
Should you determine the boot drive itself is beyond repair and needs to be replaced, the general process is as follows:
- Purchase a compatible new internal hard drive or solid state drive.
- Use disk cloning tools to copy the entire contents of the old drive to the new one.
- Or, do a clean install of your operating system on the new empty drive.
- Install the new drive into your computer in place of the old one.
- Boot from an OS installer disc and make sure the drive is detected and formatted properly.
- Reinstall your operating system, programs, and restore data from backup.
Having backups of your important files and OS installers readily available makes replacing a failed boot hard drive much less painful. With some time and patience, an inaccessible boot device caused by a non-working hard drive can usually be resolved by swapping in new storage.
Fixing Software-Related Causes
If you isolate the cause of the inaccessible boot device to be a software, firmware, or OS issue – rather than outright hard drive failure – there are also steps you can take to repair it.
For boot loader issues, try using Automatic Repair or the bootrec tool in the Windows Recovery Environment. Rebuilding the BCD store or reinstalling the boot loader may be required.
With malware infections that have damaged the boot process, use Windows Defender Offline or boot into Safe Mode to run scans that can detect and remove infections without the OS running.
Erasing and performing a clean install of your operating system can act as a reformat that gives you a fresh start. Be sure to fully back up any personal files first.
Keep BIOS/firmware updated to current versions to avoid compatibility issues. Old code bugs can sometimes interfere with booting from a drive.
Techniques like startup repair, system restore, and bootable antivirus discs can automate fixing boot problems without needing to reinstall an OS from scratch.
Preventing Boot Device Problems
While a boot device occasionally becoming inaccessible can happen to any PC or drive, there are things you can do to minimize these types of issues:
- Use a UPS to prevent unexpected power loss and potential file system corruption.
- Always safely eject/unmount drives before disconnecting to avoid potential damage.
- Keep multiple backups so you always have another copy of important data.
- Use disk utility software regularly to check for and repair errors.
- Defragment hard drives periodically to optimize performance.
- Scan drives for bad sectors and early signs of failure using S.M.A.R.T.
- Keep BIOS and drive firmware updated to latest stable versions.
- Secure your system and practice safe browsing to prevent malware infections.
- Replace aging hard drives that are past their reliable lifespan (usually ~5 years).
While you cannot guarantee a drive will never fail or develop errors, following best practices can reduce the chances of having boot issues down the road.
Recovering Data from an Unbootable Drive
If a boot device fails catastrophically and will not power on or be detected at all, specialized data recovery is likely required to extract important files off of it.
Data recovery lab specialists have equipment and techniques that can repair drives with electrical, firmware, or physical problems in order to access the data. This is an expensive service but may be warranted for irreplaceable data.
In some cases, you may be able to access data by removing the drive and connecting it as an external drive to another working computer. But if the drive has complete electrical failure this will not work.
Advanced users may also have luck with disk image software that can read low-level sectors from failing drives. But overall, crashed drives with no physical access require professional recovery.
Frequently Asked Questions
Why does my computer say boot device not found?
The “boot device not found” error indicates the BIOS cannot find an active bootable disk drive during startup. Common causes include incorrect boot order, disconnected hard drive, corrupt bootloader, drive errors, outdated firmware, or damaged system files.
Can a boot device not found be fixed?
In most cases a boot device not found error can be fixed by troubleshooting the cause. Repairing drive errors, replacing cables, correcting boot order, reinstalling bootloader, wiping drive and reinstalling OS, or updating firmware/BIOS can typically resolve the problem.
Is my hard drive damaged if I get inaccessible boot device?
An inaccessible boot device does not necessarily mean a damaged hard drive – it could be caused by software issues. But hard drive failure or corruption is the most likely hardware culprit. Trying disk repairs, replacement cables, reseating the drive can help determine if damage is the cause.
What happens if boot device fails?
If the physical hard drive containing the boot device is damaged and completely fails, the computer will be unable to start up. The drive will need to be replaced and the operating system reinstalled or restored from backup. Vital user files will also need to be recovered from backups.
Can you recover data from a dead boot drive?
If the boot drive is dead and will not power on, professional data recovery services may be able to repair it enough to recover data. Otherwise, if it spins up, attaching it as an external drive to copy files from it may work. Complete electrical failure usually requires lab recovery though.
Conclusion
The “boot device inaccessible” alert during system startup likely indicates some type of problem or disconnect between the motherboard and the boot drive. By methodically checking connections, troubleshooting hardware issues, repairing software boot problems, and ruling out hard drive failure, the root cause can usually be determined.
While an inaccessible boot device may require technical skills to fix, solutions like repairing drive errors, replacing cables, correcting the boot order, wiping the drive, or performing OS reinstallation are typically effective. Understanding the possible reasons a boot drive may not be detected helps get systems back up and running smoothly again.