How to fix the McAfee SVCHOST crash from the virus definition update

I was able to fix the virus definition debacle McAfee that is hosing a bunch of people.

It turns out, that they put in a bad signature that quarantines your SVCHOST.exe which could cause your explorer to crash. Good times, right?

So, the fix is pretty easy:

1 Restart into safe mode with networking

2 open a Command window. If your explorer isn't started, hit CTRL - ALT - DEL  and hit Task Manager. Hit File, run. CMD.EXE and enter.

3) type DEL C:Program FilesCommon FilesMcAfeeEngineavvscan.dat

4 type cd c:windowssystem32dllcache

5 type copy SvcHost.exe ..

6 Restart your PC. You are good to go!

NOTE: If you need help getting into safe mode, click here. Or, pull the power cord during the boot after seeing the LOGO. Then boot normal, which will give the boot mode option screen. Pick Safe Mode with Networking (Without networking, you can’t use your cached domain account).
Happy Coding!

0 Replies to “How to fix the McAfee SVCHOST crash from the virus definition update”

  1. This is a great tip! We have been battling this all day. We will def. send this out as a ‘Dev Tip’ to the team. Thanks!

  2. This is a great tip! We have been battling this all day. We will def. send this out as a ‘Power Dev Tip’ to the team. Thanks!

  3. Step 2 says “if your explorer isn’t started” but then you say to run CMD.exe
    This makes no sense. CMD.exe is not explorer. You need to run CMD.exe in order to execute the commands in steps 3,4,5 but this has nothing to do with explorer which is a different program.

    In step 3 you need to put quotation marks around the path/filename like this:

    DEL “C:Program FilesCommon FilesMcAfeeEngineavvscan.dat”

    Otherwise it won’t work due to the spaces in the names (Program Files and Common Files)

    1. A lot of people don’t have Explorer even working or the ability to hit Start- >Run-> Cmd.exe . Yes, CMD.EXE has nothing to do with Explorer, but Explorer was the path to get to CMD.EXE.
      So, if you follow the yellow brick road, you will get to Oz.

    1. Try changing into that directory and do a DIR on *.DAT. Does the directory even exist for you? Is the DAT there?
      Make sure you are in safe mode. McAfee locks those files otherwise and you can’t delete them.

  4. If you can get into Windows at all, you should be able to bring up a command window, even if you do not have a Taskbar. CTRL+SHIFT+ESC will bring up task manager. Click File, New Task (run), and in the subsequent window, cmd.exe, and hit the enter key. Voila! Command window appears.

  5. I am doing a search of the McAfee files from the command prompt but no subdirectory of “Engine” in my McAfee subdirectory. Any suggestions

  6. I am the same as Karen – can’t see the Engine subdirectory. But wasn’t in safe mode – would this be the reason? Also am not experiencing crashing but only have basic windows, no applications and can’t even paste except in a cmd window. Does this sound like the same issue – it was the same timing. I have read a lot about it seeming to be restricted to corporate users. I have XP SP3 and retail McAfee, but still have a serious issue.

    1. My impression was it was just corporate customers. You can do a dir /s for DAT files for your version of McAfee is storing its antivirus definitions. Just go into safe mode and delete them.
      It’s also possible you actually have a virus.

  7. First up, I suppose people should read McAfee’s article on the subject:

    https://kc.mcafee.com/corporate/index?page=content&id=KB68780

    Second, I would guess you need to boot into Safe Mode without Networking, because networking doesn’t work without svchost running (am I wrong?).

    Thirdly, I think it’s worth noting that USB memory sticks also don’t work without svchost. However, I think CD drives do.

    Finally, I would suggest it is better to have your anti-virus program working with up-to-date definitions, rather than just deleting all your .DAT files. The McAfee article describes how to fix the problem by adding a special EXTRA.DAT file. I cannot vouch for it, but this might be a better way to go if you can.

    Finally finally I offer the time-worn advice: do what you have to do, but try hard not to make the problem worse (by panicking or just not taking the greatest care you can). HTH

  8. I have the exact same problem as stewart. I followed the link that Nick sent, but this is för corporate users and when I click on the link for personal users I get an error message. Stewart, if you have solved this, please let me know how you did it.

  9. Bingo.

    Brian apologies for using your site for support but you have saved one amateur.

    Nick thanks for the post – I didn’t see the Mcafee posting in my desperate searches.

    Jonas you’ve probably already solved it – if you can get the link working the fix does work – as Nick says you’ll need to use a CD to transfer the file, not a thumb drive.

  10. Nice tips. This helped me to fix McAfee’s virus definition debacle that affected by computer. Please carry on with such great posts.

  11. This is very helpful. I thought I already need to reformat my computer. I’m very lucky that I found this post. It fixed my problem perfectly.

  12. Our office computers were down with virus. We tried to use McAfee but we can’t figure things out. Currently in the organization work for MS patches are managed. I’m sure that other customers will demand this from McAfee, so that at least it can be piloted (with a one day delay before a complete release).

  13. Its like you read my mind! You appear to know a
    lot about this, like you wrote the book in it or
    something. I think that you could do with a few pics to drive the message home a bit,
    but other than that, this is magnificent blog. A fantastic read.

    I will certainly be back.

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