How to fix
SYSTEM SCAN AT RAISED IRQL CAUGHT IMPROPER DRIVER UNLOAD Blue Screen
on Windows

I have recently received a prompt from Windows to update it. I obliged like I always do, and everything seemed to be fine. The system then rebooted, loaded to 100%, and then crashed with SYSTEM SCAN AT RAISED IRQL CAUGHT IMPROPER DRIVER UNLOAD Blue Screen error code. 

The SYSTEM SCAN AT RAISED IRQL CAUGHT IMPROPER DRIVER UNLOAD Blue Screen of Death (BSOD) error is a common issue that Windows users may encounter when attempting to apply the latest Windows updates. The BSOD is a critical error screen displayed by Windows when it encounters a fatal system error that could potentially cause data loss or system instability. It plays a crucial role in the Windows ecosystem as it helps identify and resolve issues that can disrupt normal system operation.

There are various circumstances when users may receive a BSOD, and the SYSTEM SCAN AT RAISED IRQL CAUGHT IMPROPER DRIVER UNLOAD crash is one of them. This error often occurs during the Windows update process, and it can result in users being unable to access Windows and getting stuck in a boot loop. To bypass this issue, users can enter Safe Mode and perform troubleshooting steps from there.

When users encounter the SYSTEM SCAN AT RAISED IRQL CAUGHT IMPROPER DRIVER UNLOAD BSOD, they may also see a "what failed" indication pointing at drivers such as klif.sys, mwac.sys, NNSNAHSL.sys, or other drivers. These drivers could be related to third-party software or antivirus programs that may be conflicting with the Windows update process, causing the error.

Aside from conflicting drivers, other factors that could cause this issue include corrupted system files, outdated drivers, or hardware issues. It's essential to identify the root cause of the problem to implement the appropriate solution.

One possible solution for users facing SYSTEM SCAN AT RAISED IRQL CAUGHT IMPROPER DRIVER UNLOAD BSOD or similar Windows issues is to use a reliable PC repair tool like [d1]. This tool can automatically repair corrupted files, update outdated drivers, and resolve other common Windows issues, providing a convenient and effective solution for users who may not be familiar with manual troubleshooting steps.

1. Access Safe Mode [if applicable]

If you are stuck in a boot loop and can't access Windows, you can try booting into Safe Mode instead.

• Restart your computer.
• Once Windows starts booting, press the Power button, interrupting the loading process - do this two more times.
• After that, Windows will automatically enter Advanced Startup mode.
• Select Troubleshoot > Advanced options > Startup Settings and Restart.
• After a reboot, pick either 4/F4 for Safe Mode or 5/F5 for Safe Mode with Networking.

Once you can access Windows, proceed with the troubleshooting steps below.

2. Uninstall the associated application

Once Windows is updated by Microsoft, it might cause compatibility issues with third-party security apps and files related to them. For example, klif.sys is related to Kaspersky antivirus. Therefore, uninstalling the app could solve the issue. 

• Type Control Panel in Windows search and press Enter.
• Go to Programs > Uninstall a program.
• Go through the list of the installed apps, find the antivirus, right-click, and select Uninstall.
• Follow the prompts and reboot your system.

3. Delete the associated driver

You could also remove the file that's causing Windows to crash. Since it's likely to be a driver file, follow these steps:

• Press Win + E to open File Explorer.
• At the top, go to the View tab.
• Here, mark the Hidden items checkbox.
• Navigate to the following location:
  C:\Windows\System32\drivers
• Here, scroll through the list and find the entry of the file referenced in the BSOD message, for example, klif.sys.
• Mark the file and press Shift + Del on your keyboard to delete it.

4. Uninstall the latest Windows update

Alternatively, you could uninstall the Windows update that's causing the problem. Here's how:

• Type Control Panel in Windows search and press Enter.
• Select Programs > Uninstall a program.
• Click on View installed updates on the left side of the window.
• Sort all the updates by date.
• Right-click on the most recent update and select Uninstall.
• Proceed with on-screen instructions and restart your PC.

5. Repair corrupted files

• Type in cmd in Windows search
• Right-click on Command Prompt result and select Run as administrator
• Type sfc /scannow and press Enter
• Wait till the scan is finished. Even if nothing was found or the scan returned an error, proceed with the following commands, pressing Enter after each:
  DISM /Online /Cleanup-Image /CheckHealth
  DISM /Online /Cleanup-Image /ScanHealth
  DISM /Online /Cleanup-Image /RestoreHealth
• Restart your computer.

6. Use System Restore

This option is available for those who can't access Windows and for those who can also.

• Access the recovery environment as explained at the beginning. Alternatively, press and hold the Shift key while selecting Power > Restart on the login screen.
• Go to Troubleshoot and then select Advanced options.
• Click System Restore and follow the prompts.
• Your PC will restart.