Photographs courtesy of Toby Watt - lawyer, friend and photographer extraordinaire...


Welcome to IE-Vista

Dedicated to providing advice and support to users of IE7 and IE8


Why some sites may not work with IE7

Every time a new version of Internet Explorer has been released, there have been sites that will not work with that new version.

This problem sometimes occurs because the sites in question examine something called a 'User Agent String', and then either block the browser completely if it does not recognise the version, or serve up an inappropriate page that will not work in that version of the Web browser.

Internet Explorer 7 Beta 1 introduced a new user agent string, being:
Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 6.0)

Note that the "b" has generally been used to indicate that the browser in use is a beta.

Internet Explorer 7 Beta 2 changes the string again, resolving many problems with sites that insist on sniffing UAS.  It is now:

Mozilla/4.0 (compatible; MSIE 7.0; Win32)

And then, we have Internet Explorer 7 Beta 3 onwards:

Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322)

Ok, so what do we do about the problem?  Well, we have to edit the Registry - change our system so that it pretends to have IE6 installed.  The vast majority of sites will still work, which makes you wonder why the heck they put us through such grief in the first place.

The average home user does not understand the Registry - hell, there are parts of it that even I don't understand.  If you are inexperienced you should not be messing around in there.  At worst your system will be left unbootable (caveat: the keys that we will be editing here, if damaged, will not leave your system unbootable - I am talking worst case scenario here..)

Anyway, there are REG files available for download at Fiddlertool that will make your copy of IE7 simulate other versions.  Alternatively, you can use the User Agent String Utility Tool available here.  It is a *very* cool tool that opens an Internet Explorer 7.0 window which is configured to report its identity to websites as being Internet Explorer 6.0 - an excellent way to work with Web sites that are improperly coded to only recognise IE6 and earlier.

When you run the UAS utility, you will see this window. I encourage you to choose the option to send problem URLs to Microsoft.

MS have been pro-active in addressing what they know is a real issue, contacting the owners of sites that MS knows do not work with IE7 to notify them of problems and encourage them to update, and their efforts are bearing fruit. Many Web pages that I use regularly have already been updated to suit IE7, including and But, there is only so much MS can discover on their own. If you come across a site that does not work in IE7, please use the UAS utility tool to report the problem to MS so that MS can alert the site owners and help them do what needs to be done to adjust their sites to work in IE7.

Make no mistake, there is going to be some pain for Web developers who have used various hacks and workarounds to get their sites to work with IE6. Many of those hacks are breaking in IE7, sometimes making Web sites completely unuseable - like this:

Here are a couple of URLs for the developers among us which you may find useful:

Understanding User Agent Strings

Detecting Internet Explorer more effectively

Dave Massy blogged about UAS problems on 1 September:
User Agent String Documentation

Sandi Hardmeier