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Boot

Operating System Not Found error appears

If you see the “operating system not found” symptom, possible causes include boot area corruption, system drives not recognized, etc. First check if the system drive is visible in the BIOS, then proceed with the boot sequence and Windows recovery.

Solving Order
We've organized the methods starting with the simplest and least expensive ones. Please check the solutions one by one, starting from the top.

Do you have these symptoms?

  • operating system not found
  • No operating system
  • OS not found

main causes

  • boot area corruption
  • System drive not recognized
  • Boot Mode Setting Issues

How to solve

Please check them in order from the top. If the issue is resolved, you do not need to proceed to the next step.

1

Check if system SSD/HDD is visible in BIOS

If your boot device is not physically recognized, Windows settings alone cannot fix it.

Difficulty Moderate time 5-10 minutes cost 0 won
  1. 1Enter BIOS/UEFI.
  2. 2Make sure your system SSD/HDD is listed in the Storage or Boot menu.
  3. 3If the drive is not visible, check the mounting, cables, and drive itself.

confirmation point

After these steps, see if the “operating system not found” symptom decreases or disappears. If there is no change, check for possible boot area damage in the next step.

2

Check BIOS and boot order

Determine if it is a POST or Windows phase issue and check for incorrect boot order.

Difficulty Moderate time 5 to 15 minutes cost 0 won
  1. 1Enter BIOS/UEFI.
  2. 2Check whether the CPU, RAM, and system drive are displayed normally.
  3. 3Verify that Windows Boot Manager is in the correct boot order.
  4. 4Rather than arbitrarily changing UEFI/Legacy settings, check that they match your existing installation method.
3

Run Windows Startup Repair

System file/BCD/boot record problems can be automatically fixed with Startup Repair.

Difficulty Moderate time 10~30 minutes cost 0 won
  1. 1Enter the Windows Recovery Environment (WinRE).
  2. 2Select Troubleshoot → Advanced Options → Startup Repair.
  3. 3After completion, check if it boots normally.
4

Check the same symptom in safe mode

Safe mode loads only a minimal number of drivers and services, which is helpful in narrowing down the cause.

Difficulty Moderate time 10-20 minutes cost 0 won
  1. 1Go to Settings → System → Recovery → Advanced startup.
  2. 2After restarting, select Troubleshoot → Advanced options → Startup Settings → Restart.
  3. 3See if the issue reproduces in safe mode.

confirmation point

In safe mode, if normal, third-party drivers, services, and startup programs are suspected first.

5

Revert recent changes

If the problem started immediately after installing an update, driver, or new program, a recent change may be the cause.

Difficulty Moderate time 10~30 minutes cost 0 won
  1. 1Find out when the problem first started.
  2. 2If there are any programs, drivers, or updates that were installed just before, uninstall or roll them back one by one.
  3. 3Reboot every time you make a change and check for symptoms.
6

Diagnosing RAM and system drives

If repeated recovery fails, you should check for possible memory or storage errors.

Difficulty Advanced time 30~90 minutes cost 0 won
  1. 1Check the memory and storage device using the manufacturer's hardware diagnosis.
  2. 2If there are SMART warnings or memory errors, back up important data first.
  3. 3Parts found to be faulty will be considered for replacement.

Precautions

If you need the existing data on the drive, do not initialize or format it before checking the cause.

Frequently Asked Questions

We've put together a list of things we frequently check regarding this issue.

Related issues

If the symptoms do not match exactly, please check the issue below.

Boot

No Bootable Device error appears

When troubleshooting a No Bootable Device error, it is important to rule out the causes one at a time. Based on the “no bootable device” symptom, check if the BIOS cannot find the system drive or UEFI/Legacy settings mismatch, then proceed to the next step. First check if the system drive is visible in the BIOS, then proceed with the boot sequence and Windows recovery.

View solutions →
Boot

Only the cursor blinks on a black screen when booting.

When troubleshooting a black screen with only a blinking cursor when booting, it is important to rule out the causes one at a time. Based on the “black screen with blinking cursor” symptom, check for BIOS not finding the correct boot device, boot area, or drive issue before proceeding to the next step. First check if the system drive is visible in the BIOS, then proceed with the boot sequence and Windows recovery.

View solutions →
Boot

Continuous reboot after Windows logo

Among boot problems, the “Windows boot loop” symptom may be related to driver or update conflicts or corrupted system files. Perform Windows recovery and hardware diagnostics separately based on when the repeated reboots begin.

View solutions →
Boot

Problem with beep sound and no screen when booting

If the “boot beep sound” repeats, it is better to narrow it down to memory or graphics card recognition failure or motherboard POST diagnostic error rather than changing several settings at once. Distinguish between the POST stage and the Windows startup stage, then check in that order: external device, boot settings, and recovery environment.

View solutions →

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