Fix Error Cannot Install WGA or OGA Plugin (WGAPluginInstall.exe and OGAPluginInstall.exe) in Firefox

Microsoft provides easy way to validate genuine status of Windows and Office products via Mozilla Firefox web browser with plugins support. The plugin, WGAPluginInstall.exe installs npLegitCheckPlugin.dll and nsILegitCheckPlugin.xpt, while OGAPluginInstall.exe installs npOGAPlugin.dll and nsIOGAPlugin.xpt. Both is validator that verifies that your copy of Windows XP, Vista or Office products is genuine (non-pirated).

However, the installer’s setup process only supports installation into default Mozilla Firefox path, i.e. C:\Program Files\Mozilla Firefox folder. If user has change the installation path of the Firefox web browser, the installer will not be able to find the Firefox web browser with error messages such as “Could not locate the appropriate browser directory” and “Installation Failure. Failed to copy files. [Error: 0x80070003]”.

To install the WGA-Plugin and OGA-Plugin for Firefox manually, follow these steps:

1. Download the WGAPluginInstall.exe or OGAPluginInstall.exe when prompted.
2. Extract the files from WGAPluginInstall.exe or OGAPluginInstall.exe with WinRAR.
3. There are 4 files contained inside each installer, common to both is PluginInstaller.exe and Setup.xml, while the WGA plugin has npLegitCheckPlugin.dll and nsILegitCheckPlugin.xpt or OGA plugin has npOGAPlugin.dll and nsIOGAPlugin.xpt.
4. Copy the npLegitCheckPlugin.dll or npOGAPlugin.dll to plugins folder under Mozilla Firefox directory.
5. Copy the nsILegitCheckPlugin.xpt or nsIOGAPlugin.xpt to components folder under Mozilla Firefox installation path.
6. Try to validate with Firefox browser again.

After installing the plug-in, if you wish to uninstall it, follow the WGA removal guide.