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BSoD mwac.sys

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Hi, Windows 10 20H2 fresh install, MalwareBytes Premium 4.3.0. I've had several BSoDs in the last month all naming mwac.sys as the cause, this is the first since a Windows re-install two days ago. Details below, other AV product running is HitmanPro.Alert 3.8.8 build 889. I've turned off Web Protection in MWB for now but would expect to be able to enable it at some point. Any feedback or progress with this? I see it's a fairly consistent problem for people. 

Bug check code 0x00000139
Bug check parameters





Device name:  Malwarebytes Web Protection
Driver version:
Driver path:  C:\WINDOWS\system32\DRIVERS\mwac.sys
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***This is an automated reply***


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Please try installing the newest beta for Malwarebytes which corrects several known BSOD issues with MWAC.sys.  To do so, open Malwarebytes and go to settings by clicking the small gear icon in the upper right, then scroll down to the Beta updates section under the General tab and enable the option, then scroll back to the top and click the Check for updates button and restart your system if prompted to do so.

Once that is done, test to see if the BSOD issue is resolved and let us know how it went.


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That's OK, just let us know if you encounter another BSOD, and if you don't encounter one within say a week or more (assuming you experienced it that often previously), then that should mean it's stable.

In the meantime, if you can provide the following memory dumps from previous crashes, I can ask a member of the team to take a look and see if the cause of the BSODs you experienced were the result of the issue addressed in the beta:


Since that second file listed is likely to be quite large, your best bet would be to ZIP both files and upload them to WeTransfer.com, clicking the circular ... button on the page and selecting the option to send the file as a link, then once the upload completes, post the link here.

Once the memory dumps are analyzed, they can likely provide confirmation on whether the issue should be fixed for you with the beta.

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A new version of Malwarebytes has just been released which includes fixes for several BSOD issues.  Details are available in this post.

To install the new version, open Malwarebytes and navigate to settings by clicking the small gear icon in the upper right, then click the Check for updates under the General tab and allow it to download and install the new version, restarting your system once it completes to ensure that the new components are loaded into memory.

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  • 4 weeks later...

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