My client this morning installed .NET Framework 4 on his IIS6 web server. He also updated the site I am working on to .NET 4, but now the site is serving no pages. I have just uploaded the entire site and all pages are available, yet any URL I try gives a 404 error.

Any ideas what might have happened?


You need to enable the ASP.Net 4.0 Web Service Extension.

When you run

C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i 

this installs the ISAPI filter, but doesn't actually enable it. On Windows 2003 servers you should actually run:

C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i -enable    

Do any static html files works?

Have you tried re-registering the ASP.NET extensions after installing .NET 4?

C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe /i
  • Static files are served fine. Waiting for the results of the re-register you reminded us of, thanks. – ProfK Jun 29 '10 at 7:44
  • any luck with the website? – commandbreak Jun 30 '10 at 8:42

I did the same, except I installed v3.5 ... asp pages still works fine, html works fine, but php and aspx pages just loads forever.... pages which was definitely working before the installation of v3.5


Don't know why, but .net 4 required re-start of the WWW service.
Also: so not mix .net 4 and .net 2 websites in the same app pool.

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