How To Uninstall Windows Presentation Foundation Plugin In Firefox

Martin Brinkmann
Oct 18, 2009
Updated • Feb 15, 2015

Firefox users who run Windows with the latest Microsoft .net Framework 3.5 SP1 installed may have noticed a message yesterday on browser startup that was informing them about the Windows Presentation Foundation plugin and the Microsoft .net Framework Assistant add-on.

Quite a few things puzzled many users about this: most were pretty sure that they did not install the add-on or plugin in first place which made it even more mysterious to them as it meant that some other program or someone else must have.

When they checked the plugins section in Firefox add-ons they also noticed that they could not uninstall the Windows Presentation Foundation plugin in Firefox. Only the option to disable it was provided but that is obviously not the same as removing it from the web browser.

Mozilla in the meantime has disabled the add-on using a global hotlist.

The following is a guide on how to remove the Windows Presentation Foundation plugin in the Firefox web browser for good.

If the plugin would not be blacklisted it would be possible to find out about its dll files by typing in about:plugins in the web browser address bar.

The dll NPWPF.dll is the the Windows Presentation Foundation plugin. Here are the steps to remove it from the Firefox web browser (and other Mozilla products) for good:

  • Close the Firefox web browser and every other Mozilla software that is running.
  • Go to x:\WINDOWS\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\ in windows Explorer where x is the drive letter where Windows is installed on the computer system.
  • Locate the file NPWPF.dll
  • Create a backup of the file by copying it to another location, e.g. to c:\backups\
  • Delete the dll NPWPF.dll in the Windows Presentation Foundation folder
  • Restart the computer

Open Firefox after the restart. The Windows Presentation Foundation plugin should not show up in the list of installed plugins anymore. There is a second step that may be necessary. There is also a Registry entry for the plugin. Do the following to remove the plugin from there as well:

  • Open the Windows Registry, press [Windows key R], type regedit and hit [enter]
  • Locate the Registry key HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins
  • Locate the sub-key HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins\,version=3.5
  • Right-click the sub-key and select Export to backup the key before deleting it.
  • Delete the key in the Registry
  • Restart the computer system or kill and reload explorer.exe in Windows to load the Registry without the key.

This should get rid of the Windows Presentation Foundation plugin in Firefox for now.


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  1. David Ellis said on July 16, 2012 at 2:55 pm

    I followed your procedure to the letter and backed up everything to a Quarantine folder on my desktop. When I restarted, I checked the Task Manager and WPF was still there and still running so I killed it and it popped up in a different location in the task manager list. I killed that one as well and for now it is gone. Why is it still showing up when I reboot? (Yes, I removed the registry key as suggested.)

  2. Chaoco said on May 6, 2010 at 1:41 am

    The only people who use some of those types of plugin are long term government analytics and that being said will not even be read in ten to twenty years based on your level of integrity risk affluency.

  3. Matthew Borcherding said on October 20, 2009 at 3:08 am

    I’ve coded a batch file to remove the plugin, plus the accompanying Firefox .NET extension.

    This can then be easily added to a login script or such so you can remove it from multiple systems.

    You can grab it from my blog here:

  4. Dotan Cohen said on October 19, 2009 at 11:52 am

    What is this? I thought that Window’s selling point is that it is easy to use. This is easy?

  5. Crodol said on October 19, 2009 at 2:43 am

    I have now 80 days without a restart of my computer… so cannot spoil my record now but will do when XP crashes next time or I move and need to unplug the machine.

  6. Steve907 said on October 18, 2009 at 10:59 pm

    “If the plugin would not be blacklisted it would be possible to find out about it’s dll files by typing in about:plugins in the web browser address bar.”

    A senior editor should know the difference between “its” and “it’s”.

    1. Dresandreal Sprinklehorn said on February 5, 2010 at 1:10 am

      No-one on the planet is typo free. We all make mistakes.

  7. DanTe said on October 18, 2009 at 6:54 pm

    I did a much easier solution: I just removed .Net totally from my PC’s. There’s absolutely no need for .Net except for some hack programs that requires it to run the keygen. For that, I have the .Net in a sandbox.

    Have many people remove the .Net and Microsoft loses money on their .Net marketplace. Microsoft will than have to rethink their high handed fascist ways.

    1. Bobby Phoenix said on October 18, 2009 at 7:24 pm

      Well that may work for you, but for me, and thousands of others, that is not an option. For one I run WindowBlinds, and that needs the Net framework. I know there are others that feel like we should just have the choice to install what we want. Nice try though.

    2. tunapez said on October 18, 2009 at 7:22 pm

      “I did a much easier solution: I just removed .Net totally from my PC’s.”

      Errrr, doesn’t VLC require .net to install? Comodo? It’s Sunday a.m. and I’m still foggy, but there are a few quality(not MS) programs that have prompted me to install .net framework before continuing. Seems hasty to remove completely.

      1. Sailor said on January 30, 2010 at 6:01 pm

        I have VLC without .Net

  8. Jojo said on October 18, 2009 at 11:06 am

    But what exactly do these Microsoft add-on’s actually DO? What benefit do they offer the user?

    1. DanTe said on October 18, 2009 at 6:47 pm

      To answer Jojo’s question: Microsoft offers you the “genuine advantage” of being as wide open to hacks as Internet Explorer. Now all your third party programs can be just as genuinely advantaged as Microsoft’s.

    2. Martin said on October 18, 2009 at 11:37 am

      JoJo I remember that the Framework Assistant plugin enabled one click installations, whatever that means. It is probably something that less than 1% of all Firefox users need. The WPF seems to be for rendering which suggests that it will only work on websites that make use of that technology. Again probably something that no user will ever come in contact with.

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