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Solution for 646

Windows Update

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Old 06-01-2009
Posts: n/a
error 646

I have been trying to download updatees for widows vista. I keep getting
"Windows encountered an unknown error" error 646.any suggestions as what to
do? I have at least 5 downloads my computer needs

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Old 06-01-2009
Posts: n/a
1. Open Windows Update by clicking the Start button , clicking All Programs,
and then clicking Windows Update.
2. In the left pane, click View update history.
3. Find an update for Windows that has failed to install, and then
double-click the update to view more information.
Updates that have failed to install will display Failed under Status, next
to the update name.
4. In the Windows Update dialog box, next to Error details, review the error
code for the failed update.
5. Either follow the links in the Windows Update dialog box under More
Information or Help and Support to try to fix the problem, and then try
installing updates again by using Windows Update in Control Panel or post
back with the error code so perhaps someone may be able to assist further.

<cmd_output OS="XPsp3">
E:\>set /a c = 0x646
E:\>net helpmsg %c%

Feature ID not registered.

So, I guess you had better register your feature ID?

Okay, finally, a solution. If you have Microsoft Outlook open (i.e. program
running) while you do this update, the update will be successful.

What update?
Junk filter update
Junk something...
Actually this one in particular

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Old 14-02-2009
Posts: n/a
The error code is 646. I am having the same issue.

I thought it was relevant to the original poster. Many posters fail to
provide sufficient information to assist in the diagnosis of problems.
I asked the OP for some more information, by checking the update history for
failed updates to give more clues. Just saying yo have an error code 646
doesn't mean that much really, does it?

I suggest you contact Microsoft for support issues, visit the International
Support Web site:
To make sure you receive the appropriate support information for your
location, select your region setting from the list and then click the arrow

I have been having this same problem and nothing that I do corrects it.
Vista is awful! Give those of us stuck with the trouble prone OS back XP!!

How do you register ID?
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Old 21-09-2009
Josh Davis
Posts: n/a
I think cracked the code. Open Windows Update then you should see
the "View Available Updates" link click that. Then the updates you need to
install should then be listed. Each update should be checked. Right-click
each update individually and choose "View Details". The info about the
particular update's info should come up then you should see in bold in that
window "More information:" then a link right under that. Click that and a web
page should open with a download link this is the update download page. Click
that button then run or save the installer package then proceed to execute
the installer package. Repeat the process for each ailed update! At least
that is how it worked for me.


This has just worked for me- after trying all the other suggestions which

Go to

In the search box enter the KB999999 number for each update that has failed
and click on Go. This will take you to a results screen - for me it only
found one result for each update - go to it and click on the download button
near the top of the screen.
Accept the download, click on it to run it and accept the usual warnings.
All 7 of my failed updates worked - bit of a pain when you have to reboot
after some of them.
Then in Windows Update click on Check for Updates and hopefully it will have
worked for you as well.
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Old 17-10-2009
Join Date: Oct 2009
Posts: 1
I've just used your method to download 3 updates and it worked first time.

Yes Josh that worked for me a week ago and the day after and the day after
that but after over a week of manually installing updates, this procedural
method is getting old

This didn't work for me. I'm on Vista, I've just upgraded to new version of
Norton 360, and these 5 updates wont install. I've tried installing with
Outlook open - didn't work. Why has a faulty update been released? Can
anyone help me with the next step?

I once was able to download from the support site..and correct each one...one by one, but now NO!
I hate this system just for this error problems.

Can anyone help with a simple solution. I AM NOT computer savy...so I need a simple fix (is it possible?)

I've tried installing with Outlook running and with no other programs running.
I've turned all Norton active features including Firewall off
Still stuck with 7 updates including the ones mentioned here.

These updates were ok on my laptop with Norton on it - installed without

Microsoft seem to be ignoring this problem and are hoping we will go away.

Can anyone else help?

I have about 40 updates which have failed since 10/16/09. In addition, when I click on the "Start" button in the lower left of the screen (Vista Ultimate, 64 bit), the "Shut Down" icon continuously shows the symbol for "installs updates then shutdowns your computer", even though I click on it and see updates install!

There HAS to be some systemic problem. I connect to the internet fine. Any ideas?
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Old 19-10-2009
Posts: n/a
RE: error 646

Yes I think they caused this error. Looks like everybody with a new vista OS
is having the same problem. I just bought this computer so I will be getting
win7 for free in about 2 weeks I hope then vista is gone forever for me..at
Only 1 of the 5 updates was I able to install by going to the direct links.
All the updates are as follows that refuse to install.
Security Update for Microsoft Office Outlook 2007 (KB972363)

Download size: 11.0 MB

You may need to restart your computer for this update to take effect.

Update type: Important

A security vulnerability exists in Microsoft Office Outlook 2007 that could
allow arbitrary code to run when a maliciously modified web page is opened.
This update resolves that vulnerability.

More information:

Help and Support:
Security Update for Microsoft Office Visio Viewer 2007 (KB973709)

Download size: 2.5 MB

You may need to restart your computer for this update to take effect.

Update type: Important

A security vulnerability exists in Microsoft Office Visio Viewer 2007 that
could allow arbitrary code to run when a maliciously modified web page is
opened. This update resolves that vulnerability.

More information:

Help and Support:
Security Update for the 2007 Microsoft Office System (KB972581)

Download size: 1.0 MB

You may need to restart your computer for this update to take effect.

Update type: Important

A security vulnerability exists in the 2007 Microsoft Office System that
could allow arbitrary code to run when a maliciously modified file is opened.
This update resolves the vulnerability so that the 2007 Microsoft Office
System documents are handled appropriately.

More information:

Help and Support:
Security Update for the 2007 Microsoft Office System (KB974234)

Download size: 525 KB

You may need to restart your computer for this update to take effect.

Update type: Important

This update resolves a problem that can cause programs that use the Outlook
View Control with Forms 2.0, such as Microsoft Office Outlook with Business
Contact Manager, to stop functioning as expected after Security Update for
Microsoft Office Outlook 2007 (KB972363) is installed.

More information:

Help and Support:

None of the support links seem to give any support, just the usual BS from MS
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Old 20-10-2009
Join Date: Oct 2009
Posts: 1
I had a problem with these updates too. Nothing anyone suggested would work. Then I saw that there were 7 optional downloads besides the 5 important ones, so I downloaded the optional as well and they all actually downloaded. I hope that this helps. Below is a lit of the downloads that I had. I don't know if you will have the same as me but you can try to download all of the updates to see if it works.

Security Update for the 2007 Microsoft Office System (KB974234)

Update for Microsoft Office Outlook 2007 Junk Email Filter (KB974810)

Security Update for the 2007 Microsoft Office System (KB972581)

Security Update for Microsoft Office Visio Viewer 2007 (KB973709)

Security Update for Microsoft Office Outlook 2007 (KB972363)

Office Live add-in 1.4

KME Inc. - Input - USB Human Interface Device

Microsoft Silverlight (KB974331)

Windows Live Essentials

Synaptics - Input - Synaptics PS/2 Port TouchPad

Atheros Communications Inc. - Network - Atheros AR5007EG Wireless Network Adapter

Realtek - Network - Realtek RTL8101E Family PCI-E Fast Ethernet NIC (NDIS 6.0)

I was getting frustrated everytime I tried to install the updates and they would not work, but your step-by-step instructions were the solution to my problem. Thanks for sharing!

I've been having same problem and tried all the above--updates are
downloaded, but installation always fails with the 646 error message...any
new ideas?

Same issue with no resolution, however noticed some unusal updates under optionals that include platform and runtime library updates so trying those first to see if it may correct issue before installing the failed ones.

BTW: Has anyone considered, based on the time frame this issue started to occur, that it is a ploy by MS to get us to upgrade to W7? I have never had an issue with updates until now.

I am using MS Office 2002 on Vista. I received two updates: one for Word
2002 and one for Excel 2002. Both of the updates would not install and
indicated Error Code 646. I tried all of the suggestions found here with no
luck until I applied all of the suggestions (shut down firewall, open
Outlook) and then also opened up Word and Excel and, probably most
importantly, turned OFF the Administrator User Account Control (UAC), found
at User Accounts, to allow changes to take place on the computer. The
updates installed, I restarted the computer and all is well! I have
encounted several situations where turning off the UAC allowed me to download
and, at times, uninstall programs that otherwise I was not able to do. Vista
works well, when you figure out how to navigate through it. Free MS tech
support would be appreciated for MS system issues!


I tried the Micosoft Outlook open and the update did not work for me. Anyone
with any other suggestions?

had all the same problems,,,,turned off UAC and everything downloaded just fine, checked download history and everything was passed

UAC is user account control can be found in control panel where you set administrator rights,,For info purposes I use Vista Home Premium, ,,I keep it updated all the time and run my bug killers "all" the time after being online and even when I am not online,,,all my updates are installed,,,,There is a program called BelArc that you can download, it will show you what is on your computor and what you "need", it opens like a web page but does not access the internet unless you update it,,,very good system info product
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Old 21-10-2009
Shenan Stanley
Posts: n/a
So what you are saying is the solution given several times over...

Install the updates manually.

It's not a solution, but a work around. Most who are having trouble and do
this work-around will likely be back next month (second tuesday and after)
asking the same question about how to install some update because of a
failure to install. Until they fix their updates system, it will repeat
each month.

Also - the easiest way to download any update Microsoft releases and do this
manually is to plug the KB######'s into this web page:


In this case:

From which you should click on the link for IT Professionals:

Where you can get the proper update for your version of Office.

They will also want to check the original link given to ensure they meet the
"Prerequisites to install this security update" and they might even utilize
the section on "How to obtain help and support for this security update" to
their advantage.

Yes - the conspiracy theorists have already come out.

Problem is that manyhave pushed the updates you are having issues with to
1000's of machines already. I did not have trouble on any of my personal
machines and I know many people who did not have problems with these updates
on their personal machines.

Something is wrong with *your* machine and a percentage of other people. So
far - the problem has not had a universal resolution, so the 'something
wrong' is different on a few levels/in a few ways.

Third party software changes, bum OEM installs, etc - who knows. But the
fact remains that you could run Windows XP until you bore of it. You don't
even have to update if you don't want to - I mean - you do know there are
still people running Windows 98 out there, right?

Manually download/installation means you visit the actual KB###### article
page for each and download the appropriate file to your system (save it so
you can double-click and run it later) and then reboot and install each one
individually - perhaps rebooting after you install each one successfully.

(sub in the appropriate ###### for each one)

Then visit the IT professional's page, find the appropriate file for your
system (office version, OS, etc) and click on that download link, save the
faile for running later, reboot after you have them all.

Log in as a user with administrative rights and if it is a Windows
Vista/Windows 7 machine - right-click and run as administrator for the first
update. I'd personally reboot after each one and before doing the next
one - but I *know* that is overkill.
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Old 23-10-2009
Posts: n/a
There are a lot of users having these problems. One solution is IF you
have accepted the license (try to go back and answer YES if you don?t
have done that, it`s easy to miss) -check out all questions/You maybe
have to go back & activate (under resource for example)something in a
new program you have recently installed) OR running low on diskspace
-Try to remove the latest security updates, run cleanup and
discfragment. Restart & try to update again.

Now is a great time to point you to one of the easiest ways to find
information on problems you may be having and solutions others have found:

A little deductive reasoning... You should see rather quickly - in this
context - it likely means:
User Account Control

after 4 failed attempts it worked followed the instructions here. Don't know if they all were necessary but it worked.

Opened word, excel, and outlook. turned off master account and firewall.

All eleven updates installed and automatically went to service pack two update

Kindly DISABLE/ TURN OFF the User Account Control [UAC] in Control Panel

I just want to post this as for the past several months I have had over 10 updates that I had not been able to install. I have an hp laptop so I called HP. They were unable to help me. I researched on the internet. I disabled the UAC, the pc firewall and my anti-virus firewall and they still would not go. I tried manually installing each individual update as well as many of the other solutions that people have found. As I was reading all of the posts on this web site hoping that maybe I find a solution that would finally work for me I came across someone who had said to go back and make sure that the optional updates had been installed as well. I remembered that several months ago I chose not to install a Windows Live Essentials Optional Update. I went back and installed that and ever since everything has updated without a problem. So the long and the short of it is to those of you who are still having trouble and this is something that you have not tried yet, maybe give it a try. I hope this helps someone else who has been frustrated by this. I know I was.

1.Go to the Control Pannel and under search put UAC
2. Check it out and restart computer
3.Go to updates and install updates
4. It will work and go back to UAC and check it
5. It will solve the problem

This did work and fixed the error problem. Update went through!
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Old 17-11-2009
Posts: n/a
I just solved my download problems for error 646, I've been having this
problems for 2 months and nothings seem to help. Until I read one of the post
in this forum that suggested that we try to download the optional download
which I did and it works for me!

You click on the review update and checked on the optional download and they
will prompt u to accept the license agreement, checked that too. the optional
download will be installed together with the important download. I hope this
information is helpful to all of u who has the same problems as me.

Go to start search type in MSCONFIG. click on tools then UAC. slide it down
to "do not notify" then re-boot. try windows update again and it should work.
I returned it to s normal settings and will see if I have to do this all the
time. I hope not but at least this will help

really fed up of this error now, due to issues with office 2007 - had t
reinstall, I'm up to 13 updates to install inc. office SP1, trying th
manual install route but if that doesn't work I'm buying 7 and binnin

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Old 22-11-2009
Posts: n/a
I have Vista (64bit version), and I was getting this error
for three weeks myself. Thanks to one the suggestions below, I got it to
work. The suggestion that worked for me was to "manually" install each
update "individually". I could not use the windows automatic update
feature. Here's what I did (BTW, I did not have to turn off my firewall
to do this):

1) Went to Bing.Com
2) Typed in the exact name of the update as it was displayed on the
Windows Update Screen (e.g. Security Update for Microsoft Office Excel
3) Bing found the exact match to what I typed in on the Microsoft
4) I clicked on the link
5) Selected "Download"
6) And Viola, it worked :-)
7) I repeated this step four more times, and now I've successfully
installed all five updates that I'd been trying to install for three
8) Thanks again to all of the tips people listed below, that was
helpful and the "manual" update tip worked for me.

I believe you may be correct in that this problem is being ignored.
There are loads (thousands) of reports of this on the web with no solid
I was able to do the Important Updates, manually one at a time. Very tedious
and time consuming. The Optional Updates can not/have not be done since they
don't have KB numbers and I didn't have the time to search for every last
one. This nonsense hit 2 of my machines (the newer ones) plus 2 machines of a
I got to do them all, and as I said - they have to be done one by one,
Thanks for all the help MSft - not!! And now we're supposed to buy Win7?
Yeah right.

I have been trying for weeks too. The lastest I get, when I manually try to
update is: An expected version of the product was not found on the
system...Last time I checked, I had MS Office 2007 installed so I don't know
what to do now.
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Old 08-02-2010
Posts: n/a
I was having this same problem and I came here and didn't find any answers,
so I started looking at all the stuff on the page where the error was.
Before you install the update, click on the link on the page (can't remember
what the link says) and it will give you the option to add OPTIONAL updates.
Once I did that, it installed the optional update first, then had no problem
installing the others (I'd been trying for a month now to install the
"important" update).

finally I found a solution for this error 646 ,just disconnect the network after downloading while the windows is installing if didn?t work just restart the computer and don?t connect to the internet ,go back to the windows update and press install ,because they will be already downloaded ,and it will work (vista SP2)

I know this is over 6 months now, but has anyone been able to find the
solution for error 646? I'm still unable to install the updates using all the
suggestions above.

I have three updates that won't run.

Does anyone think this could be a virus?

You need to validate your copy of Office before installing the updates. teh
Office copy may be illegimate.

I always thought Office was a bastard!

Juat turn the computer off by sliding the switch on the front of the unit and
then load the updates without the internet on and it will work
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Old 01-04-2010
Join Date: Mar 2010
Posts: 1
go into start then control panel,then auc (account user control) turn the auc off,restart computer,go into control panel and download updates,when updates have downloaded,go back into control pannel and restart the uac,and restart computer,remember to restart the uac after downloading the updates,its worked twice now for me

yes ive had the same problem,press start on your pc,go into control panel turn off the user account control,restart pc,then go into start download your updates,when done resart pc,go back into control pannel,make sure you turn the user account control back on and restart the pc,ive done this twice now each time its worked,good luck xxx by the way ime a pc novice if i can do it any one can,i found it to be the easiest way

I have a Vista 64 bit laptop, after much searching & even more frustration, here is what I personally discovered & it works for me EVERY time I get a "failed" update...ie: Error 646.
FIRST things first, I found out that if you're like me, and using Firefox....you MUST use IE browser to access Microsoft download center http://www.microsoft.com/downloads/en/default.aspx
Once there, just type a specific update (example: KB981715) in the search box, search will bring up your update. You must remain in IE to do the updates. When the page comes up with the update, click Download, a security warning box pops up..click Run or Save. It'll begin the download, another box will pop up after download, click Run. My Norton gives me a popup to give "permission to continue" (you may or may not encounter such as this). Then the appropriate update box will open & you MUST check the box at the bottom of the message to "accept Microsoft license terms" and continue. It will then "install" your specific update. If all goes as it does for me, you'll get the customary popup at the end "installation complete" click OK and you are done. To be sure it was successful you can return to Windows Update and make it check for updates again, this time your previously "failed" update should be gone. Of course, you have to do this manually for EACH failed update until all are complete.
Hope this is detailed enough to help some of you, who like me are NOT a tech (even though I don't consider myself a novice), it does get quite frustrating when otherwise well-meaning people, leave out something that seems trivial to them and is anything but that, to some of the rest of us.

A fix has been created by Microsoft for this error 646. Please go to http://www.support.microsoft.com/kb/2258121.
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Old 29-06-2010
Posts: n/a
RE: error 646

I have Windows 7, Keep getting the same error code 646 for seven different
updates. I dont have Microsoft Office, I have tried a few things I found here
but nothing is working. Does anyone have a clue of what I could do, This is
so frustrating.
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Old 14-08-2010
Join Date: Aug 2010
Posts: 1
I had this same problem with windows updates but found a simple solution. Simply Google the update number, for example, as follows:

KB2277947 Update

Then select the site to download and select "save" or "download". If you save it you will need to install it. You got it!!!

It will still appear on your update history as "failed" but but when checks are done for updates it will not appear.

The solution is simple. Google the update number, for example, as follows:

KB2277947 Update

Then select the download site and download the update. I choose to save the file normally and then install it.

You will have the update installed and if you check for updates it will not appear, although it will still show as a failed update in your update list.
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