Just got a new computer the other day (info coming soon) and only had a disk for Vista x64 RTM on hand. I loaded that on and attempted to use Windows Update to move to SP1 when I was presented with the error: 8024420C. Now I have had this error before on a previous system, however I forgot how I solved it, although I thought it was solved by downloading the offline install of SP1 and running that.
So I did that, and upon booting into SP1, found the error was still there. Much searching later I found that the error has to do with proxy settings, with suggestions like ensuring “Automatically Detect Configuration” is on in the LAN settings on Internet Options, amongst other things.
The issue here: I am not on a proxy. So after much effort searching (to no avail) I did what I usually do – suspect the firewall.
Turning off Windows Firewall gave me an immediate response, my updates now worked! Turning the firewall back on gave me the error again, and so I realised that Windows Firewall was the sole culprit here.
Morale of the story? I guess there is none, thankfully I have a NAT to protect me, and hopefully Windows 7 doesn’t have this issue.
On that note, word is that Windows 7 will enter full public beta early Jan, open to all, so if you are daring (or have a VM), give it a try, and give feedback!