Avast update resulted in no connection to websites

[Dirkus]

I have Windows XP. A couple of hours ago Avast admonished me to update. I did. Then my browser Chrome could not get connection to websites. Gmail still functioned and I could do a google search, but that was it; I could not access the websites google search supplied. Internet Explorer and Mozilla firefox did not function at all.

In the end I went back to the Windows XP safety point of 21 November and after that I had access to the websites on the Internet again.

Another, earlier, problem, which I suspect was/is also caused by Avast, is that for at least one website I get nothing except this error message: 400 Bad Request. I get the same error message for some images in a related webpage.

[DavidR]

Gmail and Google searches would be using the https protocol and as such secure connections aren't redirected and scanned by avast's web shield.

The most common cause of not being able to connect to the internet after an update is firewall blocking the avast changed components.

What is your firewall ?
Does it allow avastSvc.exe internet access ?
- If it does delete the entry for it and reconnect to the internet, this should force the firewall to ask permission again.

However, the above would only be of use had you retained the latest avast version.

[Dirkus]

I have the Microsoft firewall.

[DavidR]

OK, the XP Firewall has zero outbound checking so is unlikely to have been blocking avast.

In instances like this on update, normally we would have suggested an avast repair or failing that a clean reinstall of the latest avast version.

Since you are back on avast 8.0 you would have to choose what to do as it would require installing avast 9.0.2008 again ?

[Dirkus]

I uninstalled the old version of Avast! I installed the new version. I got the same problem and solved it again by a system reset back to 21 November. This is getting tiresome, so I have decided to not update Avast!

[DavidR]

Well a clean reinstall also entails using the avast uninstall utility to remove remnants of both installed versions.

So I'm not really sure if this is why the problem still exists. Whilst I don't use Chrome, I have no problem with avast 9.0 (currently using the latest beta build .2009) and firefox 25.0.1.

Clean install:
- Download the latest version of avast, 9.0.2008  http://files.avast.com/iavs5x/avast_free_antivirus_setup.exe and save it to your HDD, somewhere you can find it again (if you didn't save your last download). Use that when you reinstall.

- Download the avast! Uninstall Utility, avastclear.exe find it here and save it to your HDD.

• 1. Now uninstall avast! - using add remove programs, if you can't do that start from the next step, reboot.
• 2. run the avast! Uninstall Utility, it will request it be run from safe mode (and will handle the boot into safe mode),  once complete reboot into normal mode.
• 3. install the latest version, reboot.

Note: save the copy of avastclear.exe so it can be reused as some users are reporting that after running it, it is self-deleting.