Windows Security Essentials error code 0x80070424

Virus & security definitions update failed

Error code 0x80070424

Error description: Microsoft Security Essentials couldn't install the definition updates. Please try again later.

This allow prevents me from using Windows Update.

I have looked at the services.msc and I do not see Windows Update there.

Question Info

Last updated August 14, 2018 Views 27,497 Applies to:

You are seeing the effects of am ongoing hijackware infection!


NB: If you had no anti-virus application installed or the subscription had expired *when the machine first got infected* and/or your subscription has since expired and/or the machine's not been kept fully-patched at Windows Update, don't waste your time with any of the below: Format & reinstall Windows.  A Repair Install will NOT help!


OPTION A: Residents of North America (US & CA), the UK (and perhaps other regions now) may obtain Microsoft-sponsored Premium (i.e., paid) Support via the Answer Desk => [1]



OPTION B (Recommended): See...

    • Cleaning a Compromised System



If you need additional assistance with the clean install of Windows, please begin your own, new thread in this forum:


If these procedures are outside of your technical "comfort zone" - and there i

s no shame in admitting this isn't your cup of tea - take the computer to a local, reputable and independent (i.e., not a "BigBoxStore" or the Geek Squad!) computer repair shop & let them do the work.




Note: The computer should NOT be connected to the internet or any local networks (i.e., other computers) in its current state. All of your personal data (e.g., online banking & credit-card passwords) should be considered at-risk, if not already compromised.


Wish I'd had better news for you. Good luck!


I have nothing further to contribute to this discussion so I'm no longer monitoring this thread.



[1] $99.00 USD for "up to 2 hours" of remote support; fee must be paid up front; no guarantees whatsoever



[Last Revised - 11 February 2013]

~Robear Dyer (PA Bear)
Microsoft MVP (Windows Client) since October 2002

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