Wednesday, May 27, 2009

IE8 not recognized in ASP.Net 1.1 applications

As always, I install the latest versions of anything when they become available (sometimes even betas). So did I for Internet Explorer 8.0 when it was released... And all of a sudden, my trusty applications made with ASP.Net 1.1 went berzerk. Things that used to work with IE7 and Firefox simply stopped working. This included external components we bought, like the ComponentArt suite. NavBars could not be clicked, drop-down menus behaved in strange ways, and so on.

I dug a bit and found the problem. My browser was not detected as it should. The
"Request.Browser.Browser" command returned "Unknown" instead of the expected "IE". But why?

I remarked that on my Vista x64 machine, the 32 bits browser would have these issues, but not the 64 bits version of IE. I compared the "User-Agent" HTTP header and saw these values:

32 bits:
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; WOW64; Trident/4.0; GTB6; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; InfoPath.2; .NET CLR 1.1.4322; .NET CLR 3.5.21022; .NET CLR 3.5.30729; .NET CLR 3.0.30618; FDM; OfficeLiveConnector.1.3; OfficeLivePatch.0.0)

64 bits:
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Win64; x64; Trident/4.0; .NET CLR 2.0.50727; SLCC1; Media Center PC 5.0; .NET CLR 3.5.30729)

I checked the browscap.ini and machine.config files on the server, but couldn't change them in any useful way.

Could the difference in length be the problem? In a Microsoft article on TechNet ( they say that the length of this header should remain shorter than 200 characters. In the first case, it is definitely longer...

So I dug further, looking for ways to shorten that User-Agent string. Many articles and blog talked about the following key to change in the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\User Agent\Post Platform

I did this, but only the User-Agent of the 64 bits instance of IE seemed to care. I searched through the registry for the "OfficeLivePatch" key I can only see in the 32 bits instance, and found it it the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform

As you can see, there is "Wow6432Node" in there, which corresponds to 32 bits applications running on a 64 bits OS. Exactly my case ;-)

I renamed the "Post Platform" key into "Post Platform-" and restarted the browser and... bingo :-) The browser is detected as IE 8.0 and everything works fine...

Now I need to find out why, when I open a new tab or a new instance of IE 8, the content is not loaded, as it continuously shows "Connecting...". I need to open one or more tabs before a connection can be made. It also happens when opening popup windows, which is even more annoying (in that case, I need to reopen the popup with Ctrl-N until it works).

To be continued...

1 comment:

Jon said...

Thanks for posting this information, I had just update to Windows 7 Ultimate this weekend. I had VS2003 running in Vista Ultimate and did an inplace upgrade (many hours later) everything was running GREAT .. but IE was rendering my VS2003 app like it was Firefox (i did a side by side compare and they were identical). Anyway this little regedit was the ticket to making all work perfectly.