Learn How to Fix “Unknown Hard Error” on Windows 10/11

What Is “Unknown Hard Error”

“Unknown Hard Error” is an error message that appears when the Windows system encounters a serious problem. It indicates that the system cannot continue to operate normally. This error is usually accompanied by a blue screen or desktop crash.

Many factors can lead to this issue. Read the following section to get a full understanding of it.

Common Causes of Unknown Hard Error on Windows 10/11

The “Unknown Hard Error” can originate from software problems (system files, registry, updates, malware) or hardware problems (hard drive, memory). These are the common reasons:

• Software conflicts
• Virus or malware attacks
• System file corruption
• Bad sectors
• Corrupted hardware drivers
• Windows update problems
• …

Since the error message does not specify the exact issue, further investigation is needed. You can boot into Safe Mode to perform general troubleshooting or run built-in repair tools in Windows Recovery Environment (WinRE) to fix the problem.

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How to Troubleshoot “Unknown Hard Error” in Safe Mode

This section explains how to fix Unknown Hard Error on Windows 10/11 when you can access Safe Mode.

Safe Mode loads only the most basic drivers and services to troubleshoot and repair system problems.

Preliminary Work: Enter Safe Mode

Do as follows to check if you can access Safe Mode.

Step 1: Force your computer to shut down three times consecutively during startup. On the fourth startup, the system will automatically boot into WinRE.

Step 2: Select Troubleshoot > Advanced options > Startup Settings > Restart.

Step 3: In the Startup Settings page, press F5 to enter Safe Mode with networking.

If Safe Mode cannot be accessed, go to the next section to perform operations in WinRE.

If you successfully enter Safe Mode, try the following repair methods.

Fix 1: Turn off or Uninstall Your Antivirus Software

Sometimes antivirus software can block or corrupt critical system files and operations, causing “Unknown Hard Error”. Disabling or uninstalling it can help fix the error.

To turn it off:

Step 1: Click the upward arrow in the bottom right corner to show the hidden icon.

Step 2: Right-click the antivirus software icon and select Quit, Exit, or a similar option (Usually at the bottom).

To uninstall it:

Step 1: Type Control Panel in the Windows search bar and press Enter.

Step 2: Click Programs and Features, right-click the antivirus software, and select Uninstall.

If the issue persists after disabling the antivirus app, try the following methods.

Fix 2: Scan for Viruses

Malware or viruses can corrupt system files and processes, causing the boot error. Here is how to scan for viruses.

Step 1: Press Win + I to open the Settings app and click Update & Security.

Step 2: Switch to Windows Security and click Virus & threat protection.

Step 3: Click Scan options. Then choose a scan method and click Scan now.

If the error still exists, proceed with the next option.

Fix 3: Run CHKDSK to Repair Disk Errors

File system corruption or bad sectors can lead to this error. CHKDSK is designed to check the file system and bad sectors, and attempt to repair disk errors. Here is how to run it.

Step 1: Type cmd in the Windows search bar, right-click Command Prompt, and choose Run as administrator.

Step 2: Input chkdsk E: /f /r and press Enter. The letter E should be replaced by the actual letter of your drive.

When the process ends, check if the error message disappears.

Fix 4: Run System File Check (SFC)

DISM and SFC (System File Checker) commands are used to help repair corrupted or missing protected Windows system files that may be causing the error.

Here is how to execute DISM and SFC.

Step 1: Open Command Prompt with administrative privileges.

Step 2: Type DISM /Online /Cleanup-Image /RestoreHealth and press Enter.

Step 3: Continue typing SFC /scannow and press Enter.

Wait for the process to complete. If this method doesn’t work, attempt the next one.

Fix 5: Reinstall the Problematic Drivers

Problematic drivers can be one of the reasons for this error. Reinstalling them helps get your computer back to normal.

Step 1: Press Win + R, type devmgmt.msc, and press Enter to open Device Manager.

Step 2: Right-click the suspicious driver (commonly graphics card drivers, storage controller drivers, and audio drivers) and select Uninstall device.

Step 3: Go to the hardware manufacturer’s official website (such as NVIDIA, AMD, Intel, Realtek, and motherboard manufacturers) to download the latest version of the driver.

After installation, restart your computer to see if the issue is fixed.

Fix 6: Uninstall the Latest System Update

A recent system update may introduce bugs or compatibility issues, leading to the Unknown Hard Error or other startup problems. Uninstalling the problematic update may help resolve the issue.

Step 1: Open Settings and click Update & Security.

Step 2: In the Windows Update section, click View update history.

Step 3: Click Uninstall updates at the top.

Step 4: Right-click the recent update and select Uninstall.

If the problem remains, attempt a System Restore.

Fix 7: Perform System Restore

Performing System Restore in Safe Mode can revert your computer’s critical system files and settings to a previous stable state. This may undo system or software changes that caused the error.

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How to Fix “Unknown Hard Error” in WinRE (Cannot Access Safe Mode)

This section explains how to fix “Unknown Hard Error” in WinRE. Try these methods one by one.

Preliminary Work: Boot to WinRE

Force shut down the computer three times in a row until it boots into WinRE.

After booting successfully, start performing operations.

Fix 1: Launch Startup Repair

Launching Startup Repair can automatically detect and repair common problems that prevent Windows from starting normally.

Step 1: In WinRE, select Troubleshoot > Advanced options.

Step 2: Click Startup Repair to detect and repair common problems.

Fix 2: Uninstall Recent Updates

Follow the steps below to uninstall recent updates in WinRE.

Step 1: In the Advanced options page, click Uninstall Updates.

Step 2: Choose one uninstallation method between the following two options. The system will automatically roll back.

• Uninstall latest quality update: remove recent minor patches
• Uninstall latest feature update: remove the recent major version update

Fix 3: Execute CHKDSK

Here is how to run CHKDSK to repair disk errors in WinRE.

Step 1: Click Command Prompt in the Advanced options page.

Step 2: Type chkdsk E: /f /r and press Enter. Replace E with the drive letter of your drive.

Fix 4: Run DISM and SFC

Run DISM and SFC in WinRE according to the following steps.

Step 1: Open Command Prompt in WinRE.

Step 2: Type the following commands and press Enter after each:

• DISM /Online /Cleanup-Image /RestoreHealth
• SFC /scannow

Fix 5: Execute System Restore

Do the operations as follows to perform System Restore in WinRE.

Step 1: In the Advanced options interface, click System Restore.

Step 2: Select an account, enter the correct password, and click Continue.

Step 3: Choose a restore point and follow the on-screen instructions to complete the process.

How to Recover Files Before Performing a Clean Install

If all methods fail, try the last resort – perform a clean install.

Step 1: Recover Data from a Non-booting PC

A clean installation will completely erase all files on the system disk. Therefore, transfer or recover your data from the non-booting computer to an external hard drive in advance.

Option 1: Copy files to an external hard drive in WinRE

Windows allows you to copy files on your computer and paste them to an external hard drive in WinRE using Notepad. Follow these steps to do it.

Step 1: In the WinRE Command Prompt, type notepad and press Enter.

Step 2: In the Notepad window, click File > Open.

Step 3: In the pop-up window, locate and right-click the needed file, and select Copy.

Step 4: Open the external hard drive, right-click the blank area, and select Paste.

Option 2: Use MiniTool Power Data Recovery Bootable to recover data

Using MiniTool Power Data Recovery to recover data from a crashed computer is another choice.

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The Bootable edition of this software allows you to create bootable media (e.g., USB or CD/DVD) to boot and recover data from computers that cannot start.

It is capable of restoring almost all file types, such as documents, pictures, videos, audios, and more.

The tool features an intuitive and straightforward interface, allowing you to perform data recovery with ease.

Here are the steps to recover files:

Phase 1: Create the bootable USB recovery drive

1.1. On a working computer, download MiniTool Power Data Recovery Bootable, and insert an empty USB drive.

1.2. Open the software and click the Bootable Media icon in the upper right corner.

1.3. In the MiniTool Media Builder window, select the WinPE-based media with MiniTool plug-in option.

1.4. Follow the on-screen wizard to create a bootable USB drive.

Phase 2: Boot the crashed computer from the USB drive

2.1. Insert the bootable USB drive into your crashed computer.

2.2. Restart the computer, and then immediately press the BIOS key to enter the BIOS (common keys are F2, F12, Delete, or Esc).

2.3. In the Boot menu, change the boot order to make the USB drive the first boot device.

2.4. Press the F10 key to save and exit. The computer will boot into the MiniTool PE interface.

Phase 3: Scan the target drive and recover data

3.1. In the MiniTool PE page, select MiniTool Power Data Recovery.

3.2. In the main interface, select the specific partition or disk that contains the lost data and click Scan. 

• Logical Drives: It shows all detected partitions.
• Devices: It shows all physical disks connected to your computer.

3.3. After the scan completes, locate the target files using Path, Type, Filter, and Search.

• Path: It lists files according to file structure.
• Type: It displays scan results by file types.

Besides, the Filter and Search can help locate files faster.

• Click the Filter button and set the file type, modification date, file size, and file category as needed.
• Type a full or partial filename in the Search box and press Enter to locate the specific file.

3.4. Double-click the found files to preview.

3.5. Check the files you want and click the Save button.

3.6. In the new window, choose an external hard drive to save the recovered files and click OK to start recovery.

Once recovery is finished, connect the external drive to the working computer and verify that the files are intact and accessible. If they are, continue with the next step.

Step 2: Perform a Clean Install

Follow the steps to reinstall Windows.

Step 1: Prepare an installation media

Insert an empty USB drive into the working computer. Then visit the Download Windows 11 page. Under Create Windows 11 Installation Media, click Download Now.

After downloading, double-click MediaCreationTool.exe, then follow the wizards to create a bootable USB drive.

Step 2: Boot from the installation media

Connect the USB drive to your problematic computer. Restart the device, then press the appropriate startup key to enter the BIOS.

Go to the Boot tab, set the USB drive as the primary boot option, then press F10.

Step 3: Start the installation process

The system will boot from the USB drive and enter the Windows Setup interface. Now choose your preferred language, time format, and keyboard layout, then click Next.

In the Choose installation options window, select Install Windows 11 > I agree that everything will be removed, including files, apps, and settings.

Step 4: Delete existing partitions and install

On the Select location to install Windows 11 screen, delete all partitions on Disk 0 until only Unallocated Space remains. Select the Unallocated Space and click Next.

On the Ready to Install screen, click Install. The computer will automatically restart several times during the installation process.

Once it is complete, you will enter a brand-new Windows system without the “Unknown Hard Error” error.

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To Sum Up

In a word, this post outlines how to fix Unknown Hard Error on Windows 11/10.

• If you can access Safe Mode, try disabling or uninstalling antivirus software, running SFC, reinstalling drivers, uninstalling recent updates, and performing System Restore.
• If Safe Mode cannot be accessed, enter WinRE and try advanced options, such as Startup Repair, Uninstall Updates, and System Restore.
• If all approaches fail, recover data using MiniTool Power Data Recovery first, and then perform a clean install.

For any questions about the MiniTool product, contact us at [email protected].