Windows 10 upgrade experience - BSOD on mfewfpk.sys


Did an upgrade to Windows 10 on a consumer laptop today. In general the upgrade went well. I’m still amazed by all that it seems to do, i.e. it takes a significant amount of time, but that doesn’t take a way from the fact that the upgrade in itself succeeded and Windows 10 was installed in the end.

Then, after having installed the last remaining updates, Windows 10 didn’t start anymore. To be a little bit more precise: the updates started installing, then Windows 10 reboots with the intention to finish the installations, but then it doesn’t start.

The blue screen (BSOD) noted that the driver mfewfpk.sys causes an irql_not_less_or_equal error.

After searching on the internet for a bit, I found this Windows 8.1 to 10 upgrade support page. The page gives you a few options, but you’ll still have to choose and try. So I thought that I should describe the path I took, which works for me.

  1. Boot into Safe Mode (is it still called Safe Mode?) by repeatedly pressing F8 during the (Windows) boot process. Choose to troubleshoot the issue (advanced options) and click on the command prompt.
  2. Move the driver (it is a file), which is located in %SYSTEMROOT%\system32\drivers\mfewfpk.sys to a different location outside of the Windows system, say c:\temp-backup-of-crashing-driver\mfewfpk.sys.
    Note that this driver is not essential for Windows to boot. So after having moved this driver file, you will find that Windows cannot load the driver anymore and it again boots normally.
  3. (Cleanly) Shut down the system and retry booting Windows 10 normally. If you have the same issue as I did, then this will now work. Watch the update installations being finished.
  4. Once Windows 10 is booted, update installations are finished and you’re logged in and the desktop is fully loaded, you might want to run the McAfee consumer product removal tool. This should clean up any other remaining drivers and files that were still on the system.
    Note this laptop shouldn’t have the driver installed in the first place, as there were no McAfee products installed. So I suspect a bad uninstaller forgot to remove the driver and it was actually still loaded all the time.

For this particular situation, there weren’t any McAfee products installed. I suspect this problem might have been caused by an earlier installation package that got McAfee Security check software stuffed in. So even if you think you do not have any McAfee products installed, it’s a good idea to run the McAfee consumer product removal tool referenced in step 4.

This post is part of the Windows 10 upgrade experience series.
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