MozillaZine

Issues related to plugins

From MozillaZine Knowledge Base

This article explains how to identify and disable installed plugins in Firefox and Mozilla Suite/SeaMonkey and includes a list of some problematic plugins used by Mozilla browsers on Windows.

If you are having problems with your Mozilla browser and you think that it might be related to an installed plugin, you should perform the standard diagnostic steps first, to rule out problems caused by other issues such as problematic extensions or other profile issues. If you already know that your issue is related to a specific plugin because of problems with certain web content or because you received an error message identifying the plugin, you should first look through the articles in the Category:Plugins for a solution.

Note: Starting in Firefox 3 and SeaMonkey 2, you will be able to view, disable, and enable plugins using the Add-on Manager, accessible from the Tolls menu ("Tools -> Add-ons (Add-on Manager) -> Plugins"). [1]

Contents

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Background

Mozilla browsers often need plugins for web content that cannot be handled internally, such as Java applets, Flash movies and embedded audio and video. (Note that JavaScript is often required for Flash to run correctly. Note also that JavaScript is neither a plugin nor Java.) Mozilla browsers find installed plugins by searching in different locations [2].

On Windows, some common plugins are located via plugin scanning; other plugins are detected in the Mozilla browser installation directory "plugins" folder (e.g., in Firefox, C:\Program Files\Mozilla Firefox\plugins). If different plugins for the same MIME type are found in multiple locations, the plugin found in the installation directory plugins folder will normally be used.

Some plugins are known to cause problems or can interfere with other plugins. One way you can diagnose problems you suspect are plugin-related is by removing or disabling the plugin. If the problem goes away, it was caused by the plugin. Keep in mind that if you disable or remove a plugin, embedded web content handled by that plugin will be missing and you may receive a "missing plugin" alert.

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Identifying installed plugins

You can see a list of detected plugins by entering about:plugins in the Location Bar (address bar). The installed plugins list will include the file name and a description of the plugin along with the associated MIME types handled by each plugin. On Windows, all Mozilla browser plugin file names begin with np and end with .dll. (Note that some plugins like Quicktime or Java include multiple plugin files, each with a different file name.) If you set the plugin.expose_full_path preference to true in about:config, you will be able to see the full path to each plugin file in the about:plugins list, instead of just the file name.

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Mozilla Default Plug-in

On Windows, Mozilla browser installations include the Mozilla Default Plug-in "npnul32.dll", located in the browser installation directory "plugins" folder. Mozilla Suite and SeaMonkey need this plugin for the "click here to get the plugin" alert on web pages that need plugins that are missing. Firefox does not require this plugin as the "Additional plugins are required..." yellow message bar will display without it.

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Disabling plugins found in the plugins folder

Applies to Windows systems

You can temporarily disable some of the plugins that your Mozilla browser is detecting by renaming or removing the associated files from the installation directory "plugins" folder, as follows:

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Firefox

  1. Completely exit Firefox.
  2. Open the Firefox "plugins" folder (e.g., C:\Program Files\Mozilla Firefox\plugins).
  3. Do one of the following:
    • Rename each "np*.dll" file by adding an "X" before the name, or
    • Remove all of the files in the plugins folder to a backup location.
  4. Restart Firefox.

If the problem persists, you should check the about:plugins list again to see what plugins are still being detected via plugin scanning. Additionally, some programs that include browser plugins such as Quicktime may copy back any removed plugin files to the browser plugins folder.

If the problem goes away, it was caused by one of the disabled plugins. You can try to identify the problematic plugin and restore the other plugin files or you can simply reinstall any missing plugins as needed.

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Mozilla Suite or SeaMonkey

Follow the same procedure given above, except do not rename or remove the Mozilla Default Plug-in "npnul32.dll" from the Mozilla Suite or SeaMonkey installation directory "plugins" folder, since this file is needed for missing plugin alerts (see above).

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Disabling the automatic plugin scan

Applies to Windows systems

On Windows systems, Mozilla browsers will scan for common plugins in other locations, even if the browser plugins folder is empty. You can prevent the automatic scan for for common plugins such as Windows Media Player or Real Player by modifying the related preference settings. For detailed instructions, see this article. Note that some plugins that are detected via plugin scanning such as Java or Adobe Reader can be disabled by other methods, described below.

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Other methods of disabling plugins

  • You can disable Java in your browser settings to prevent Java applets from running. This will help determine whether the Java plugin is causing your issues such as a persistent browser process after exiting Firefox, Mozilla Suite or SeaMonkey. Other Java-related issues include high memory use, browser hangs and security problems.
  • (Windows) You can disable the Adobe Reader browser plugin to force .PDF links to open the Adobe Reader program instead of the Adobe Reader plugin, which, if done via the Adobe Reader program preferences, should remove the "nppdf32.dll" plugin file from all locations (see the Adobe Reader article for additional information).
  • You can disable Quicktime plugins for different filetypes via the Quicktime browser settings from within the MIME settings window, by unchecking the file formats you don't want opened by the associated Quicktime plugin. Note that you may have multiple Quicktime plugins depending on how many file types you have enabled in the Quicktime browser settings.
  • Firefox only: If you just want to disable the plugin for file download actions, but leave the plugin enabled for embedded files, this can be done via your Firefox options for managing file types, as explained in this article.
  • You can install an extension to block content that requires a plugin. For example, the Flashblock extension will block Flash and Shockwave content and NoScript can be configured to block Flash and other plugins [3].
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Problematic plugins

Applies to Windows systems

Your Mozilla application, a Mozilla extension or the application that includes the plugin may provide a user interface where a problematic plugin can be disabled. See the other methods of disabling plugins given above.

In some cases, there is no user interface and you must manually disable the plugin by renaming or removing the plugin file itself. The following plugins, which are known to cause problems in Mozilla applications, must be manually disabled:

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Plugins folder

To disable these plugins, you must close your browser and either remove the associated np*.dll file from your Mozilla application's plugins folder and place it in a backup location or rename the plugin file. To rename the plugin, add an "X" in front of the file name.

  • npyaxmpb.dll - The Yahoo! activeX Plug-in Bridge plugin may causes crashes when using Yahoo Mail (see the linked article).
  • npmozax.dll - The ActiveX plugin will conflict with the the Flash plugin or cause other problems if the wrong version is installed.
  • npvlc.dll - The VLC Media Player plugin can cause a conflict with the Windows Media Player plugin and cause problems viewing Windows Media Video files.
  • npunagi2.dll - This is the AOL Media Playback Plugin. It launches AOLMediaPlaybackControl.exe to play embedded .MP3 files but doesn't work properly [4].
  • npbittorrent.dll - The Bittorrent plugin can cause an empty Download Actions list of file types.
  • np32dsw.dll - The Shockwave plugin can cause an immediate increase in memory usage. Either uninstall the Shockwave Player, or disable the plugin by removing or renaming the plugin file.

Download manager plugins are known to cause problems downloading or saving files, if the application is later uninstalled or otherwise stops working, if the associated plugins are still in place. Such plugins include:

  • NPGetRt.dll (GetRight) [5]
  • NPWinGet.dll (WinGet) [6]
  • npdap.dll (Download Accelerator Plus) [7]
  • npfd.dll (FreshDownload) [8]
  • NPNXCatcher.dll, NPNXCatcher(Audio).dll, and NPNXCatcher(Video).dll (Net Transport) [9]

Information about other Download Managers can be found at PluginDoc.

Outdated versions of plugins that may have been placed in the plugins folder may conflict with the currently-installed version.

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Plugins found in other locations

To disable these plugins, you must close your browser, find the location of the plugin and either remove the associated "np*.dll" file to a backup location or rename the plugin file by adding an "X" in front of the file name.

  • npYState.dll - The Yahoo! Application State plugin file "npYState.dll" can cause Yahoo Mail to crash. To disable the plugin, open the C:\Program Files\Yahoo!\shared folder and rename the file "npYState.dll" to "XnpYState.dll". Open Firefox and test Yahoo! Mail.
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Related bug reports

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See also

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