The Mozilla Default Plug-in

By default, Mozilla Firefox comes with the file npnul32.dll in the \Plugins\ directory. If you enter about:plugins in the location bar, you’ll see a list of installed Plug-ins, with file information, and MIME-type assignments. In that list, you’ll see npnul32.dll listed as “Mozilla Default Plug-in”, assigned to the MIME-type *.
So what is the Mozilla Default Plug-in? What does it do? Why is it there? Can one disable it? How does one disable it?

The Mozilla default plug-in is the plugin finder that gets initiated, when you try to load a page that requires a plug-in, which is not found. Whether or not the default plug-in is enabled or disabled dictates how the plugin finder works.
For instance, if don’t have the Macromedia Flash plug-in, then go to their test page, this is what you’ll get with the default plug-in disabled:

This is what you’d get, if the default plug-in is enabled (click on it for full size):

To enable the Mozilla Default plugin, use about:config to change the pref plugin.default_plugin_disabled to false

16 Responses

  1. Luccks February 1, 2006 / 3:18 pm

    Tank’s for your post. I resolve my problem, exactly same. []’s

  2. Karie February 22, 2007 / 12:18 am

    I recently updated to Firefox 2.Now, websites are not loading correctly. I can no longer see all images and backgrounds,or colors on web sites.
    I have tried changing settings, updated all plugins-I have tried everything that the Firefox help forums have suggested.I also tried enabling the mozilla default plugin as you described above.Any other ideas? This is driving me crazy!

  3. jennifer March 10, 2007 / 12:50 am

    Karie…I have the exact same problem as you after installing Firefox 2…did you find any solution.


  4. Jason March 27, 2007 / 11:05 am

    Thanks for the troubleshooting tips! That’s been bugging me for months.

  5. Diane April 21, 2008 / 2:10 pm

    I believe this is why I could not download my class videos. Thanks.

  6. viktor May 18, 2008 / 1:59 pm

    thanks man!! that solved my problems, i love you:P

  7. viktor May 18, 2008 / 2:05 pm

    What!!! i cant it does no difference if i enable plugin.default_plugin_disabled to false :S it worked before

  8. Drmarx May 22, 2008 / 11:45 pm

    I want to know firefox can automatically download the missing plug ins like IE does.

  9. mdda July 20, 2008 / 1:38 am

    Haha! Downloading plugins automatically is the massive security hole that is the downfall of IE. DO NOT WANT.

  10. ulligaka September 12, 2008 / 11:28 am

    Brilliant it worked like a charm for me (firefox Remember to restart firefox to make it work.

  11. Ben September 24, 2008 / 9:41 am

    it didnt work

  12. Don December 19, 2008 / 11:33 am

    Is this plug in installed and enabled in update firefox 3.05 ?

  13. Bashiieru August 30, 2009 / 7:33 pm

    Duudee thank you soooooo much, aru! 8D

  14. Alan Baxter October 24, 2009 / 10:26 am

    You appear to have been hacked. View Source shows there is a hidden iframe with a link to a malicious site at the end of the page. I’ve broken the link here.

  15. Alan Baxter October 24, 2009 / 11:03 am

    “I’ve broken the link here.”
    Apparently the link was stripped from my comment. Just look for the hidden iframe.

Comments are closed.