--- title: Telerik MVC issues with IE 11 description: .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. image: https://www.inalign.com/hubfs/BlogSitefinity/sf-hero-plain-code-orange.jpg --- - [About](https://www.inalign.com/about-us) - [Code](https://www.inalign.com/custom-development) - [Sitefinity](https://www.inalign.com/sitefinity-development) - [Blog](https://www.inalign.com/sitefinity) - [Contact Us](https://www.inalign.com/contact-us/) # Telerik MVC issues with IE 11 by [Gregg Crystal](https://www.inalign.com/sitefinity/author/gregg-crystal) Jan 06, 2014 .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(). ![Telerik MVC issues with IE 11](https://www.inalign.com/hs-fs/hubfs/BlogSitefinity/sf-telerik-issues-ie11.png?width=511&name=sf-telerik-issues-ie11.png "Telerik MVC issues with IE 11") In IE 11, I can use the developer tools to set the user agent string to IE 10, and things work normally again. ![sf-telerik-issues-ie11-02.png](https://www.inalign.com/hs-fs/hubfs/BlogSitefinity/sf-telerik-issues-ie11-02.png?width=394&height=130&name=sf-telerik-issues-ie11-02.png) 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). Hot Fixes: - [2836939](http://support.microsoft.com/kb/2836939/en-us) .NET 4 - Win7SP1/Win2K3SP2/Win2K8R2SP1/Win2K8SP2/VistaSP2/WinXPSP3 - [2836940](http://support.microsoft.com/kb/2836940/en-us) .NET 3.5 SP1 - Win2K3SP2/Win2K8SP2/VistaSP2/WinXPSP3 - [2836941](http://support.microsoft.com/kb/2836941/en-us) .NET 2.0 SP2 - Win2K3SP2/WinXPSP3 - [2836942](http://support.microsoft.com/kb/2836942/en-us) .NET 3.5 SP1 - Win7SP1/Win2K8R2SP1 - [2836943](http://support.microsoft.com/kb/2836943/en-us) .NET 2.0 SP2 - Win7SP1/Win2K8R2SP1 - [2836945](http://support.microsoft.com/kb/2836945/en-us) .NET 2.0 SP2 - Win2K8SP2/VistaSP2 - [2836946](http://support.microsoft.com/kb/2836946/en-us) .NET 2.0 SP2 - Win8RTM/WinRTRTM/Win2K12RTM - [2836947](http://support.microsoft.com/kb/2836947/en-us) .NET 3.5 SP1 - Win8RTM/WinRTRTM/Win2K12RTM *Reference: [http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/internet-explorer-11-user-agent-string-ua-string-sniffing-compatibility-with-gecko-webkit.aspx](http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/internet-explorer-11-user-agent-string-ua-string-sniffing-compatibility-with-gecko-webkit.aspx)* *[![Ready to Supercharge Your Sitefinity Project](https://no-cache.hubspot.com/cta/default/413787/04646b54-51ba-42b1-95ad-140ebc8c1440.png)](https://cta-redirect.hubspot.com/cta/redirect/413787/04646b54-51ba-42b1-95ad-140ebc8c1440)* ### Related Posts [![10 Sitefinity Features Marketers Can Easily Use with Any Website](https://www.inalign.com/hubfs/Inalign_March2018/Layout/sitefinity-background-supercharge-4.jpg)](https://www.inalign.com/sitefinity/10-sitefinity-features-marketers-can-easily-use-with-any-website) [10 Sitefinity Features Marketers Can Easily Use with Any Website](https://www.inalign.com/sitefinity/10-sitefinity-features-marketers-can-easily-use-with-any-website) [![What PHP Developers Need to Know When Working With Sitefinity](https://www.inalign.com/hubfs/BlogSitefinity/sf-hero-plain-sf-people-at-computers-blue.jpg)](https://www.inalign.com/sitefinity/what-php-developers-need-to-know-when-working-with-sitefinity) [What PHP Developers Need to Know When Working With Sitefinity](https://www.inalign.com/sitefinity/what-php-developers-need-to-know-when-working-with-sitefinity) [![Running Sitefinity Locally Within IIS on Windows 10](https://www.inalign.com/hubfs/BlogSitefinity/sf-hero-plain-charts-blue.jpg)](https://www.inalign.com/sitefinity/running-sitefinity-locally-within-iis) [Running Sitefinity Locally Within IIS on Windows 10](https://www.inalign.com/sitefinity/running-sitefinity-locally-within-iis) [![Speeding Up Sitefinity Development: Inline Editing](https://www.inalign.com/hubfs/BlogSitefinity/sf-hero-development-blue.jpg)](https://www.inalign.com/sitefinity/speeding-up-sitefinity-development-inline-editing) [Speeding Up Sitefinity Development: Inline Editing](https://www.inalign.com/sitefinity/speeding-up-sitefinity-development-inline-editing) [![Solution to the Sitefinity Error: The located assembly's manifest definition does not match the assembly reference.](https://www.inalign.com/hubfs/BlogSitefinity/sf-hero-crash-org.jpg)](https://www.inalign.com/sitefinity/sitefinity-error-assembly-manifest-does-not-match) [Solution to the Sitefinity Error: The located assembly's manifest definition does not match the assembly reference.](https://www.inalign.com/sitefinity/sitefinity-error-assembly-manifest-does-not-match) [![How to Customize Module Builder Widget Templates with Conditional Statements](https://www.inalign.com/hubfs/BlogSitefinity/sf-hero-plain-charts-orange.jpg)](https://www.inalign.com/sitefinity/how-to-customize-module-builder-widget-templates-with-conditional-statements) [How to Customize Module Builder Widget Templates with Conditional Statements](https://www.inalign.com/sitefinity/how-to-customize-module-builder-widget-templates-with-conditional-statements) [More](https://www.inalign.com/sitefinity/topic/sitefinity) --- ### Subscribe to Our Blog --- ### Topics - [Recent](https://www.inalign.com/) - [Inbound Marketing](https://www.inalign.com/topic/inbound-marketing) - [Technology](https://www.inalign.com/topic/tech-marketing) - [Manufacturing](https://www.inalign.com/topic/industrial-manufacturing) - [Energy](https://www.inalign.com/topic/retail-energy) - [Sitefinity](https://www.inalign.com/sitefinity) --- [![5 Conversion Killers Every Marketer Should Avoid](https://no-cache.hubspot.com/cta/default/413787/80197558-1902-4342-bb36-b0d3da7222ec.png)](https://cta-redirect.hubspot.com/cta/redirect/413787/80197558-1902-4342-bb36-b0d3da7222ec) ## This Post Was Written by Gregg Crystal CEO and Founder of Inalign, Inc. (www.inalign.com), a full stack Software Development firm specializing in building web and line of business applications. We focus on .NET, Angular, SQL Server, and Sitefinity. Connect with me: ### About Inalign [Visit Inalign.com](https://www.inalign.com) ### Visit Us On LinkedIn [Visit LinkedIn](https://www.linkedin.com/company/inalign-inc) ### Check Out Our Portfolio [Visit Portfolio](https://www.inalign.com/Portfolio/portfolio-home/) ### Get a Free Assessment ![inaligngraylogo](https://www.inalign.com/hs-fs/file-1175323414-png/Inalign/Images/inaligngraylogo.png) ## 800.602.9947 - [Code](https://www.inalign.com/custom-development) - [Sitefinity](https://www.inalign.com/sitefinity-development) - [Blog](https://www.inalign.com/sitefinity) - [About](https://www.inalign.com/about-us) ## ABOUT INALIGN Inalign is a full stack Software Development firm specializing in building web and line of business applications. We focus on .NET, Angular, SQL Server, and Sitefinity. 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