If you’ve tried to install recommended updates in Windows Vista, and receive error 800B0100, this tutorial offers the most common solution to that problem.

- The solution, in a nutshell, is to disable your firewall. If you’re using McAfee Personal Firewall Plus, F-Secure Internet Security, Norton Internet Security or another Firewall vendor, see its respective support page for assistance in disabling it (temporarily). If you’re using the built-in Vista Firewall, keep reading.
Open the Control Panel and select Security.
- Select Turn Windows Firewall on or off.
- Select Off (not recommended), click Apply and then OK.
- Back at the Windows Update screen, click the Try again button.
- The download(s) and installation should start…
- and this time successfully install. If a restart is required, make sure to re-enable your Firewall once your PC restarts.
- Though this solution will work for most Vista Update errors, see the Microsoft search results for the error 800B0100 if it doesn’t work for you.



























I have been reading up on this issue for a long time now. I have two Dell machines – an Inspiron Laptop and a Dimension 9150 Server.
My laptop upgraded to Sp1 with no problems at all. The Dimension however has been a bit of a pig and I have seen this 800B0100 code for a good long time.
I have tried pretty much every step I could find, both here on TechNet and elsewhere. Nothing worked.
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edit: Not for nothing, but I am not some noob either, I have been in the industry for 15 years and some of the KB articles offered as resolutions are a complete nightmare even for a *ahem* talented professional, so I’d hate to know how someone without any real experience would cope…
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What I did was quite simple really, a little bit of a pain to accomplish but it’s RESOLVED THE ISSUE FOR ME.
I simply performed an “in-place upgrade” i.e. re-installed Vista and used the upgrade option.
Then came the nightmare…
After re-installing, I ran Windows update and let nature take it’s course…
After about 6-10 updates and reboots, I was finally offered SP1, which I was finally able to download and install.
Hope someone, somewhere finds this helpful because I have seen a lot of you out there still struggling with this one.
Neither of these fixes worked in my particular case however I found another solution. If neither of the above fixes work for you try searching for the update that keeps failing manually. In my case it was KB938123. Every time I tried to update I got the above error message. I searched for ‘download KB938123′ on google and downloaded it to my desktop from the microsoft web site. I then performed a normal manual install. After that the laptop downloaded updates normally.
Olá. Já tentei efectuar da forma como indicam mas nada feito, continua na mesma, na conseguem instalar a actualização.
Obrigado.
I HAVE TRIED EVERYTHING TO GET MY MEDIA CENTER TO LAUNCH BUT IT WON’T IT KEEPS GIVING ME THIS MESSAGE THAT MEDIA CENTER HAS STOPPED WORKING AND I CAN’T FIND THE REASON DOES ANYONE HAVE ANY IDEAS –THANKS
我原來就設定關閉了.但一直出現那代碼更新都一直不成功耶
aqui não funcionou e continuou dando o erro 800b0100
He seguido esos pasos y nada, me sale el mismo error
I had already disabled my firewall by stopping the service entirely. It actually turned out that i coulnt install update because of this..
Enabling the firewall service again, allowed me to continue the install.. Oddness