Plugins are part of third-party software you installed on your computer. In order to uninstall the plugin, you'd need to remove the application which installed the plugin in the first place. That isn't always desired. I'd therefore just keep those unwanted plugins disabled. They won't do any harm. There are ways to adjust the Windows registry so that those plugins are not visible to Firefox anymore, and hence won't show up in the add-on manager. But unless you know exactly what you're doing you should not start messing with this.

You can view where each of your Plugins are located on system (whether on Windows, Mac OSX or Linux) by typing about:plugins in the Location (address) bar.

Complete removal of old plugins is critical to Firefox operation. At least it has been on my machines.

I had the latest Firefox 40.0.2 installed on some older WindowsXP/SP3 boxes. Firefox would run, but if more than 3 or 4 tabs were open, I would typically get a crash. The crash always indicated "plugin-container.exe" as the module that triggered the crash. I had Java, Java Deployment Toolkit plugins, VLC, WIndows Media Player, and the two Microsoft DRM plugins, plus Shockwave Flash and the Cisco OpenH264 Video codec plugin. All were set to "Never Activate" (ie. disabled) except Flash. Firefox crashes were a daily problem. The failing module was *always* "plugin-container.exe". The transmission of problem reports/crash dumps also always failed, despite settings being adjusted to send crash reports.

Removal of the non-active/obsolete plugins seems to have corrected the crash issues. I currently have 11 tabs open, and can flip between all of them, without problem. Video also works. (Note: have also just installed AdBlock plus *extension* (not a plugin). It works very well.)

Please note: Some have suggested "Reseting" Firefox to default values. This will *NOT* affect recognized plugins. It will just delete your extensions, such as AdBlock.

To remove/delete plugins, so Firefox cannot see them, you can do the following:

The global way: (Method 1)

 (If the plugins are being loaded via a registry scan...)
 1) open a tab, and select "about:config:"  In the search dialogue box,
    enter string "plug"
 2) Scroll until you find parameter:  "plugin.scan.plid.all" which will 

be set to "true". Right-click to bring up option box, and choose "Toggle" to set the value to "false". This will stop Firefox from scanning the registry to load plugins. Some of your plugins will disappear. (check your current plugins, by opening a Firefox tab, and entering "about:plugins" All the details of your installed/available/visible plugins will be shown) Once you have reset "plugin.scan.plid.all" to "false", any plugins that are showing up via a registry scan will be gone.

The problem with Method 1 is it may not whack all plugins. AND, it WILL whack your Adobe Flash plugin for sure. This is a problem, of course, as you will get no video in your Firefox on most sites...

So, Method 2:

 Look at the details in "about:plugins" and find the path names to the 

.dll files. The pointer info to run the .dll's is in the registry, but if you just rename the file, so it cannot be found, Firefox will just skip the loading/referencing of the plugin.

 Eg:  I had an old VLC plugin installed to "C:\program files\VLC" called

"npvlc.dll". Just navigate to the directory, and rename the .dll file to something like "NoRun_npvlc.dll" If at some point you want to restore the operation of the plugin, just rename the file back to its original name. Once the .dll file is renamed, it will be deleted - or at least not seen by Firefox.

And Method 3: You can also, for some plugins, tweak the minimum version number inside the Firefox "about:config" parameter space, to some level that is really high. That will just prevent the plugin from loading. This is a good way to disable the Microsoft Windows Media Player plugin stuff. In my version of Firefox (version 40.0.2), the value for the minimum usable version was set to "7.0" I just changed the string value to "999.0", and that prevented the plugin for the Media Player from loading, as well as removing the Microsoft DRM crap. Again, this is in "about:config", in the list of parameters that show up after searching for "plug".

You highlight the parameter, press right click, and then select the "Modify" option to change the value from "7.0" to "999.0". This is a kludge, but it stops the plugin from loading, yet does no damage to the Media Player configuration, nor do you need to mess around with fiddling the values of the Registry Keys. Eg:

     "plugin.scan.WindowsMediaPlayer"             was  => "7.0",
      now becomes:                                 => "999.0"

I also had Java 7.0 and the Java Deployment Toolkit being found as plugins. The references were in the registry (a really quite bad place to put them), but if you just find the two .dll's, which are "npjp2.dll" and "npdeployJava1.dll" and rename them to something like "turnoff_npjp2.dll" and "turnoff_npdeployjava1.dll", you can re-activate them if you need to at some later date, but they will now not show up in the Firefox list of active/non-active plugins, and will be effectively deleted, as far as Firefox is concerned.

Much of this info is from Martin Brinkman's 2009 stuff on his site: "www.ghacks.net/2009/10/18/how-to-stop-automatic-plugin-installations-in-firefox". (It also explains how to disable/remove plugins). The .js stuff (as he explains in updates) is no longer user-configurable, but the removal options he indicates appear to still work. Martin, you are a scholar and a gentleman.

"Deleting" the old plugins, so they now do not show up, seems to have resolved the regular crashing of Firefox on my machines. Also, the methods described here can be implemented without adjusting or changing any registry key data.

I would urge those doing development on Firefox to take a hard look at the "plugin-container" module, and to also consider giving users a simple method to effectively remove *plugins* from Firefox. Since I removed the old plugin references, Firefox seems to be running crash-free. I have 11 tabs open as I write this, and that was never possible prior to this plugin cleanup exercise. Hope this info is useful.

Note that you can set via the plugins.enumerable_names pref what plugins a website can detect via the navigator.plugins array (default is '*' to detect all plugins). This pref is a comma delimited list of plugin names as seen on the about:plugins page. Setting the pref to Shockwave Flash will make a website only see the Flash plugin.

• plugins.enumerable_names = Shockwave Flash

You can test that by typing navigator.plugins in the Web Console (Firefox/Tools > Web Developer).

You need to close and restart Firefox after modifying this pref.

Thanx for that suggestion, cor-el. I appreciate the info. Since you are moderator, could you do me great favour and remove my two posts to another thread/question about deleting plugins? I posted a terrible, intemperate rant, quite unacceptable, to another thread "how to delete plugins". I also then posted what I learned about deleting plugins to that other thread, but that thread is now closed and I cannot now edit/delete my awful ranting complaint. I am greatly embarrassed by the rude tone and nature of that first post, and would appreciate it greatly if you or someone could remove it. It was inappropriate, and I apologize for violating the necessary rules of etiquette.

I am running Firefox 40.0.2 on an old HP Pentium 4 WinXP/SP3 box, and although I am reasonably sure there is no malware present, it is possible I might have a driver incompatibility issue somewhere, which may account for some of the Firefox crash activity I've been experiencing. Of course, I need to upgrade both the hardware and the software.

So, I will be upgrading much of my equipment soon, and I really need to complment all the developers and contributors involved with Firefox. I recently put together a CentOS 6.6 Linux machine, and was pleased to see Firefox 31.1.0 ESR was bundled in the distro. Firefox is a great open source effort, and for a lot of us out at the edge of web, it has become a critically important tool that enables us to work, communicate, and live an important part of our lives. Thanx to everyone who has contributed.

And yes, folks, upgrade your equipment. We recently purchased a Macbook Air, and were able to install and use Firefox on it also. And we are also running it on several Android tablets, both 4.x and 5.x versions of Android O/S. Great product, and good proof of what the open-source approach can deliver.

Bottom line, it is possible that old plugins are not responsible for my crashing problems on Firefox. I just determined I have an older Dell laptop running WinXP/SP3, with current Firefox, and have a similar bunch of non-active plugins, and I am having no problems with that machine, despite its use as a streaming video-player most of the time. - R. F.

gemesys Sep 2, 2015 12:29:38 PM was his rely to me. I did not find it inappropriate, but actually amazingly helpful - though I have not had a chance to try them yet. Will report back. You could use more support techs like him, plus he credits Martin Brinkman which I bet others wouldn't.

Cor-el -side note to pass on... I get the survey request "Do you want to help make Mozilla Firefox better?" at the very beginning, before I've even had an opportunity to do anything. Should this not come at the end?