--- title: "How to: Detect Whether the .NET Framework 3.5 Is Installed" ms.date: "03/30/2017" helpviewer_keywords: - "verifying whether.NET Framework 3.5 is installed [WPF]" - "detecting .NET Framework 3.5 installation [WPF]" - "detecting whether.NET Framework 3.5 is installed [WPF]" - "determining whether.NET Framework 3.5 is installed [WPF]" ms.assetid: 8556a9d2-1eb8-48ef-919c-5baf22a2a9a2 --- # How to: Detect Whether the .NET Framework 3.5 Is Installed Before administrators can deploy Windows Presentation Foundation (WPF) applications on a system that targets the .NET Framework 3.5, they must first confirm that the .NET Framework 3.5 runtime is present. This topic provides a script written in HTML/JavaScript that administrators can use to determine whether the .NET Framework 3.5 is present on a system. > [!NOTE] > For more detailed information on installing, deploying, and detecting the .NET Framework, see [Install the .NET Framework for developers](/dotnet/framework/install/guide-for-developers). ## Example When the .NET Framework 3.5 is installed, the MSI adds ".NET CLR" and the version number to the UserAgent string. The following example shows a script embedded in a simple HTML page. The script searches the UserAgent string to determine whether the .NET Framework 3.5 is installed, and displays a status message on the results of the search. > [!NOTE] > This script is designed for Internet Explorer. Other browsers may not include .NET CLR information in the UserAgent string. ```html Test for the .NET Framework 3.5
``` If the search for the ".NET CLR " version is successful, the following type of status message appears: `This machine has the correct version of the .NET Framework 3.5.` `This machine's userAgent string is: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; InfoPath.2; .NET CLR 3.0.590; .NET CLR 3.5.20726; MS-RTC LM 8).` Otherwise, the following type of status message appears: `This machine does not have the correct version of the .NET Framework 3.5. The required version is v3.5.0.0.` `This machine's userAgent string is: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; InfoPath.2; .NET CLR 3.0.590; MS-RTC LM 8).` ## See also - [Detect Whether the .NET Framework 3.0 Is Installed](how-to-detect-whether-the-net-framework-3-0-is-installed.md)