Windows Defender Doesn't Download Updates



Windows Defender on my computer has not downloaded definitions since 8/31.
(Windows Update History shows that definitions were downloaded on 9/3, but
that does not show up in the Window Defender home page. I did a System
Restore last week, restoring the computer to 8/31. I don't know if that's
the cause of my problems or not.) Defender does not update when I manually
check (claims there are no updates available, even though I'm pretty sure
there are by now) and doing a manual check for updates in Windows update
doesn't do anything, either. What can be done to fix this?


I am having the same problem. The last update was 8/31, and the icon in the
notification area asks me to check for updates (although it is set to update
automatically daily prior to each scan), and clicking on "check for updates"
results in the message that there are no new updates available.


Glad it's not just me. I have the same notification message as you do.

In case there's anyone out there that can help, I guess I should add that I
am using Vista 64-bit, McAfee Security Center, & the definition listed in
Defender is

I saw that you can manually download updates on Microsoft's website. Are
those updates cummulative, so that if I downloaded the latest definition, the
previous updates that I've missed out on would also be included in that


Here's McAfee phone # 1-800-338-8754. You'll most likely get a person in
India. They will walk you through solving your problem. Windows Defender
needs to be disabled when using McAfee Security Suite 2009.

Consider going to the secuÑity portal


and downloading the 64-bit definitions for Windows Defender to the desktop,
*right* click mpas-fe.exe and choose 'Run as administrator'
to apply.

See if that both brings you up to date, and perhaps improves on the behavior
in future.

I hope this post is helpful.

Let us know how it works ºut.

Good luck




I should have indicated that while RM is using McAfee, I am not. However, I
am already running Windows Defender as Administrator.

Bill Sanderson

McAfee may not be relevant to the problem. You can certainly try the same
cure as posted for RM--go to the security portal, as both Engel and I have
posted. In your case, download the 32-bit Windows Defender definitions,
unless you know that you are running a 64 bit version of Windows.

The definitions at the portal are cumulative, and will bring you current.
If Windows Update is otherwise functional, they will likely result in
automatic updates resuming as expected, too. If WU is not working, you need
to get that fixed asap.


Thanks everyone for your help. I was able to download the update through the
security portal. How often are the Defender updates released through Windows
Update? Should I be concerned if they don’t start showing up in Windows
Update again?

How often are other Windows updates released? (Perhaps my Windows Update
isn’t working correctly. It checks for updates, but hasn’t found any new
ones since last Tuesday, 9/8.)

Bill Sanderson

Updates aren't released on any particular schedule. You can be reasonably
certain that new ones will be available every second Tuesday, because that's
the schedule for critical security updates--but there could be a month
without one for your particular Windows version...

The definitions at the portal are the most current, period. They may be
updated multiple times per day. Definitions at WU are less frequent--but
still, in my experience, usually more than once a day.

I wouldn't worry too much about WU unless you get an explicit error message.

Is there any chance that your machine is part of a corporate or
institutional network where WU is going to a WSUS (or in-house) server,
rather than Microsoft's servers directly?


No, I don't think so. It's just a home PC on a wireless network.

Could my doing a System Restore (on 9/6 to 8/31) have messed up my computer?
After I did that, the Defender definitions reverted to 8/31 and never
re-downloaded the 9/3 definitions - which was the latest on my computer - or
any subsequent definitions. However, perhaps whatever problems that may be
going on are only Defender-related, as Windows Update downloaded critical
security updates on 9/8.

Bill Sanderson

Re-doing the definitions, via a download from the security portal, should
fix things if the System Restore is the root cause--and you may be right


That's interesting, I had also done a system restore but it hadn't occurred
to me that this might have been at the root of the problem. Thanks all again.

Bill Sanderson

I'm not sure why that should be, but I suspect that the update process is
expecting to be able to use a delta update--I.e. one which only includes
changes since the last update, and, in fact, needs a FULL update. It is
possible that this would fix itself on the next distribution which includes
a full update. The downloads from the security portal are always full
updates, so they should both bring you current, and enable future updates to
be delta updates.

The delta updates are quite a bit smaller, so there's advantage for everyone
as long as they work...

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