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Firefox Add-ons to Support .NET Application Deployment

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The Windows Presentation Foundation (WPF) plug-in for Firefox and the .NET Framework Assistant for Firefox enable XAML browser applications (XBAPs), loose XAML, and ClickOnce applications to work with the Mozilla Firefox browser.

Warning

XBAPs require legacy browsers to operate, such as Internet Explorer and old versions of Firefox. These older browsers are usually unsupported on Windows 10 and Windows 11. Modern browsers no longer support the technology required for XBAP apps due to security risks. Plugins that enable XBAPs are no longer supported. For more information, see Frequently asked questions about WPF browser-hosted applications (XBAP).

WPF Plug-in for Firefox

The WPF plug-in for Firefox enables XBAPs and loose XAML files to be navigated to and run at the top-level or in an HTML IFRAME in the Firefox browser. An XBAP is a WPF application that can be published to a Web server and launched within supported browsers. Loose XAML is a XAML-only file that can be navigated to and displayed in supported browsers, much like an XML file.

The WPF plug-in for Firefox is installed with the .NET Framework 3.5. Window 7 includes the .NET Framework 3.5, but does not include the WPF plug-in for Firefox. You cannot install the WPF plug-in for Firefox on Windows 7.

The .NET Framework 4 does not include the WPF plug-in for Firefox. However, if both the .NET Framework 3.5 and .NET Framework 4 are installed, the WPF plug-in for Firefox is installed with the .NET Framework 3.5. Therefore .NET Framework 4 applications will still run because the WPF Host will load the correct version of the framework. For more information, see WPF Host (PresentationHost.exe).

.NET Framework Assistant for Firefox

The .NET Framework Assistant for Firefox enables stand-alone ClickOnce applications to run from the Firefox browser. The .NET Framework Assistant for Firefox functions identically when it is installed before and after the Firefox browser. When the Firefox browser is launched and the .NET Framework 3.5 SP1 is installed, Firefox finds and installs the .NET Framework Assistant for Firefox. Users can configure the .NET Framework Assistant for Firefox to do the following:

  • Prompt before running the ClickOnce application.

  • Report all installed versions of the .NET Framework or just the latest version.

The .NET Framework Assistant for Firefox is included with the .NET Framework 3.5 SP1. For information about removing the .NET Framework Assistant for Firefox, see How to remove the .NET Framework Assistant for Firefox.

See also