FIX: Driver irql not less or equal (mfewfpk.sys) error

Ivan Jenic
by Ivan Jenic
Troubleshooting Expert
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Driver irql not less or equal (mfewfpic.sys) BSOD

As you know, Windows 10 is available as a free upgrade to all genuine Windows 8 and Windows 7 users, however, the upgrade process to Windows 10 isn’t always smooth and some users report getting driver_irql_not_less_or_equal (mfewfpk.sys) error.

Driver_irql_not_less_or_equal (mfewfpk.sys) is usually followed by a Blue Screen of Death after which your computer restarts.

This error is caused by a file mfewfpk.sys that is related to McAfee Security Software, and usually, the best solution to this is to remove McAfee security software before upgrading to Windows 10.

If you have already upgraded to Windows 10, don’t worry, there’s still a way to fix this issue.

How to fix Driver_irql_not_less_or_equal (mfewfpk.sys) error?

1. Uninstall McAfee

To do this, you will need to download and run McAfee removal tool. You can download it from here. After you’ve downloaded the tool, you just need to run it and it will remove McAfee Security Software completely from your computer.

If you’re getting Blue Screen of Death with driver_irql_not_less_or_equal (mfewfpk.sys) error then you probably won’t be able to access your Windows 10 and download McAfee removal tool, so you’ll have to start your Windows 10 in Safe Mode.

2. Start Windows 10 in Safe Mode

  1. While your computer boots keep pressing F8 or F2 or Shift + F8. This will sometimes allow you to access Advanced Boot Options.
  2. If it doesn’t work, after your computer resets for several times you’ll get the option to Restart or to enter Advanced Startup. When this happens make sure that you choose Advanced Startup.
  3. Then choose Troubleshoot.
  4. Next, you need to go to Advanced Options > Startup Settings.
  5. When you enter Startup Option you’ll have the option for Safe Mode with Networking. Choose it, and download the McAfee removal tool from the link above.
  6. Run the McAfee removal tool to remove McAfee software completely.
  7. Restart your computer. After you’ve removed McAfee Security Software everything should be working as usual.

If the problem is resolved after removing McAfee, you might want to keep using Windows Defender or switch to a different antivirus solution.

Windows Defender offers solid protection, but if you want full system protection, it might be wise to install third-party antivirus software.

Here’s a list of the best antivirus software for Windows 10.

3. Move the problematic file to a different directory

  1. Start Windows 10 in Safe Mode. To see how to do that, be sure to check the previous solution for detailed instructions.
  2. When Safe Mode starts, open File Explorer and go to C: WindowsSystem32drivers directory.
  3. Now locate mfewfpk.sys file and move it to a different location, outside of the Windows directory.

After doing that, restart your PC and the problem should be completely resolved. Keep in mind that this isn’t a system file, so you can also remove it if you want.

In most cases, this problem is caused by mfewfpk.sys, and in order to fix this issue, you need to find and move the file to a different location. This file is located in the Windows directory, but it’s not crucial for Windows, so you can easily move it.

4. Use Linux boot drive

If driver_irql_not_less_or_equal (mfewfpk.sys) error is preventing you from starting Windows, you might be able to fix the problem simply by booting from a Linux boot drive.

To create a Linux boot drive, you download Linux ISO on a working PC and then create boot drive using Rufus or any other similar tool.

After doing that, you need to connect the boot drive to your PC and boot from it. Once you start your PC in the Linux environment, you need to find C: WindowsSystem32drivers directory and move or remove mfewfpk.sys file.

Keep in mind that in a Linux environment your drive might not be labeled as C, so you’ll have to find the Windows directory on your own.

This is a bit advanced solution, so if you don’t know what is an ISO file or Linux, and if you don’t know how to create a bootable drive, you might want to read a tutorial or two or try a different solution.

4. Use Command Prompt to remove the file

  1. Right-click the Start Menu button or press Windows Key + X. Now choose Command Prompt (Admin) or PowerShell (Admin).
    Driver irql not less or equal crash
  2. When Command Prompt starts, run the following command: DEL /F /S /Q /A “C: WindowsSystem32driversmfewfpk.sys.
    Driver_irql_not_less_or_equal (mfewfpk.sys)

This command will force Windows to remove this file. After doing that, just restart your PC and check if the problem is resolved.

5. Run CCleaner in Safe Mode

If you’re getting Driver_irql_not_less_or_equal (mfewfpk.sys) error, you might be able to fix it by running CCleaner in Safe Mode. If you’re not familiar, CCleaner is a great tool that can remove junk files and registry entries.

In doing so, this application can also fix many problems on your PC.

To fix this issue, many users are advising to enter Safe Mode, download CCleaner and run it. Once you start it, scan for issues and perform a registry scan. Keep in mind that you need to repeat the scans until no issues are found.

After doing that, restart your PC and check if the problem is resolved. Several users reported that CCleaner managed to solve the problem for them, so be sure to try it out.

If you can’t manage to follow the steps you can read another method of fixing this issue. 

6. Perform a System Restore

  1. Restart your PC a few times during the boot sequence to force your PC to boot to start Automatic Repair.
  2. A list of options will appear. Select Troubleshoot > Advanced options > System Restore.
  3. Now select your username and enter your password.
  4. System Restore window should now appear. Click on Next to proceed.
    Driver irql not less or equal mfewfpk sys
  5. If available, check to Show more restore points option. Now you should see several restore points available. Check the date and time for each entry and select the desired restore point. Now click on Next.
    Driver irql not less or equal mfewfpic.sys BSOD
  6. Follow the instructions on the screen to restore your PC.

After performing a System Restore, your PC should be restored to an earlier state, and the problem should be resolved completely. Keep in mind that this isn’t a perfect solution, and sometimes even the System Restore won’t be able to fix your problem.

7. Use Windows 10 installation media to perform Automatic Repair

  1. Connect the bootable drive to your PC and boot from it. In order to boot from the USB drive, you might have to change your boot settings in BIOS.
  2. Once you from your boot drive, click on Repair your computer option.
  3. Now choose Troubleshoot > Advanced Options > Automatic Repair.

The Automatic Repair process will now start. This process can take 10 minutes or more, so don’t turn off your PC. Once the repair process is finished, check if the problem is resolved.

Before you start, you need to download Windows 10 ISO using the Media Creation Tool and create a bootable drive. You can do that from Safe Mode or from a working PC.

We hope these solutions helped you with Driver_irql_not_less_or_equal (mfewfpk.sys) error, if you have any questions, or comments, just reach for the comment section below.

FAQ: Read more about the irql not less or equal (mfewfpk.sys) error

  • What does Irql_not_less_or_equal mean?

The irql_not_less_or_equal means that you have a problem caused by a file called mfewfpk.sys that is related to McAfee Security Software.

  • How do you diagnose blue screen?

The BSOD can be caused by hardware problems on your computer. You can test the RAM for errors and also try to check its temperature because it might be overheating. Of course, other components can be the problem too. Test them or just as the help of a professional.

  • How do I know if I have bad drivers Windows 10?

Bad driver issues trigger various computer glitches. Some of the most common problems include the following: BSOD errors, sudden computer crashes, computer lag, and more.

  • Editor’s Note: This post was originally published in January 2020 and has been since revamped and updated in March 2020 for freshness, accuracy, and comprehensiveness.
Editor's Note: This article was originally published in November 2015 and was revamped and updated in April 2020 for freshness, accuracy, and comprehensiveness.
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