.NET 4.0 (or earlier) doesn’t recognize the user agent string used by IE 11.
This is only an issue for web applications that do user agent sniffing.
Telerik MVC components do user agent sniffing and pages that use them blow up in IE 11.
Below is an example of that error, you'll see it dies on Telerik().StyleSheetRegistrar().
In IE 11, I can use the developer tools to set the user agent string to IE 10, and things work normally again.
Microsoft released hot fixes for .NET that will address this issue. Alternatively, installing .NET 4.5 on the server will fix the issue where websites are running .NET 4.0 (.NET 4.5 supports the IE 11 user agent string).
- 2836939 .NET 4 - Win7SP1/Win2K3SP2/Win2K8R2SP1/Win2K8SP2/VistaSP2/WinXPSP3
- 2836940 .NET 3.5 SP1 - Win2K3SP2/Win2K8SP2/VistaSP2/WinXPSP3
- 2836941 .NET 2.0 SP2 - Win2K3SP2/WinXPSP3
- 2836942 .NET 3.5 SP1 - Win7SP1/Win2K8R2SP1
- 2836943 .NET 2.0 SP2 - Win7SP1/Win2K8R2SP1
- 2836945 .NET 2.0 SP2 - Win2K8SP2/VistaSP2
- 2836946 .NET 2.0 SP2 - Win8RTM/WinRTRTM/Win2K12RTM
- 2836947 .NET 3.5 SP1 - Win8RTM/WinRTRTM/Win2K12RTM