Windows BSOD Error 0x00000079 — MISMATCHED_HAL Fix

What Does This Error Mean?

Error 0x00000079 means there is a mismatch between the Hardware Abstraction Layer (HAL) and the Windows kernel. The HAL is the layer that lets Windows talk to your hardware — think of it as a universal translator between Windows and your computer's components. If the HAL and kernel do not match, Windows cannot start. This most commonly happens after manually copying system files or swapping a hard drive between computers.

Affected Models

Windows 10
Windows 11
Windows 8.1
Windows 7
Windows Server

Common Causes

The Windows kernel and HAL files were replaced with mismatched versions
A hard drive with a Windows installation was moved from a different computer with different hardware
Manually copying system files from another Windows installation mixed incompatible versions
A failed or partial Windows update replaced some kernel files but not the matching HAL
Third-party imaging or cloning software restored mismatched system components

How to Fix It

Run Startup Repair from the Windows Recovery Environment. Turn the PC off three times during boot to trigger recovery, then choose Troubleshoot > Advanced options > Startup Repair.

Startup Repair can detect and fix HAL and kernel mismatches in many cases by restoring the correct matched files.
Restore the correct HAL using the recovery Command Prompt. Open Command Prompt in the recovery environment and run: sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

SFC will detect that system files are mismatched or corrupted and replace them with correct versions from the component store.
Use DISM to repair the Windows image. In recovery Command Prompt, type: DISM /Image:C:\Windows /Cleanup-Image /RestoreHealth — restart after it completes.

DISM repairs the component store that Startup Repair and SFC use as their source for correct files.
Roll back to a System Restore point if available. In the recovery environment, choose Troubleshoot > Advanced options > System Restore and pick a date before the problem started.

A restore point created before the mismatched files were introduced will undo the damage.
Perform a Windows repair install. Boot from a Windows USB installer and choose to upgrade the existing installation. This replaces all system files including the HAL and kernel with a fresh matched set.

This is the most reliable fix for this specific error. Your personal files and most applications are preserved.

When to Call a Professional

If you moved a drive from another computer and cannot get Windows to boot, a technician can perform a repair install or help migrate the installation properly. This error is difficult to fix without access to recovery tools, so professional help may save significant time.

Frequently Asked Questions

What is the HAL (Hardware Abstraction Layer)?

The Hardware Abstraction Layer is a layer of software that sits between the Windows kernel and the physical hardware. It translates generic kernel requests into specific commands your hardware understands. Different computers need slightly different HAL versions depending on their CPU type and hardware configuration. If the HAL file does not match the kernel file, Windows cannot start.

Can I move a Windows hard drive from one PC to another?

Technically yes, but it often causes problems — including this error. Windows installs drivers and configures the HAL for the specific hardware it was installed on. Moving the drive to a different computer means the HAL may not match the new hardware. The best approach is to use the Windows repair install on the new machine to rebuild the correct configuration.

This happened after a Windows update. How do I undo it?

If the update caused the mismatch, try uninstalling it from the recovery environment. In the Windows Recovery Environment, choose Troubleshoot > Advanced options > Uninstall Updates. If that is not available, use System Restore to roll back to before the update was installed.