Using Old Extensions (Add-ons) in Firefox 3

Firefox 3 Download dayDid you download Firefox 3 already?

Yesterday, the Download Day, was a big day for Firefox as it released its latest version 3.0. When the Download Day was first announced last month, I pledged to download the free browser within 24 hours after it’s release to help set a Guinness record.

I have been using FF for years and always got the latest update when it became available. While FF is great, the biggest headache as I experienced is its memory consumption. I am using quite a few extensions and always have a lot of tabs opened. If I don’t restart the browser for a couple of days, its memory usage just keeps growing. It’s not rare to see that Firefox uses some 700MB of my memory. I have tried many memory tweaks with pretty much no luck. Since Firefox 3 is supposed to do a better job in keeping memory usage under control, I decided to get the browsing software as soon as it is released.

Anyway, I got the software yesterday and it looks good so far. The only problem is that the browser is up-to-date, but not all the add-ons. Some of my favorite ones have been disable due to incompatibility with FF 3. One of them is called AutoCopy, which allows me to copy the text by just selecting it, no Ctrl-C needed. It’s a very convenient extension. Losing it all the sudden caused a lot of pain.

So I searched a little bit and found this workaround to let me continue using the add-on until the FF 3 compatible version is available.

  1. Download the AutoCopy add-on file (you can find one at here, then right-click to Save Link As);
  2. Change the file extension from .xpi to .zip (from autocopy-v0.6.4.xpi to and use your file compression/decompression application such as WinZip or 7-Zip to extract the files;
  3. Find the install.rdf file in the extracted file folder and open it with a text editor (Notepad);
  4. In the file, find this section
  5. <!– Firefox –>

    and replace 2.0.0.* with 4.0.0.* and save the file.

  6. Drag and drop the install.rdf file onto the file. It will ask whether you want to overwrite (or add) the file, install.rdf, to the archive. Confirm;
  7. Change the file from back to its original name autocopy-v0.6.4.xpi;
  8. Grab the autocopy-v0.6.4.xpi and drop it into your FF browser. A window will pop up:
  9. install Firefox add-ons

     Click the Install Now button once it becomes clickable and the install will begin.

However, the installation may fail if another window pops up with the following error message:

old add-on

If this happens to you, then there’s a little extra work to be done before you can enjoy your old extensions. According to this discussion, the above problem can be easily fixed by adding a new value to the Firefox configuration:

  1. Open a new tab and type about:config in the address bar;
  2. Right click inside the window and select New->Boolean;
  3. A new window will pop up and enter extensions.checkUpdateSecurity as the preferred name;
  4. Set the default value to false in the next window;

Now repeat Step 7 in the above installation process and you will see the following window:


Restart your Firefox and enjoy your favorite, old extensions again :)

I have used this method to install two more add-0ns, MinimizeToTray and Page Title Eraser, and they all work like they used to so far. This method may not work with all the add-ons, so you have to try to see. Until those extensions get updated, I will keep the extensions.checkUpdateSecurity value and use this workaround.

This article was originally written or modified on . If you enjoyed reading this post, please consider subscribing to my full RSS feed. Or you can also choose to have free daily updates delivered right to your inbox.

Author Info

This post was written by Sun You can find out more about Sun and his activities on Facebook , or follow him on Twitter .

8 Responses to “Using Old Extensions (Add-ons) in Firefox 3”

  1. Racha |  Jun 20, 2008 at 5:42 am

    wow fantastic help. I was totally flustered without autocopy. your work around is awesome.

    “Restart your Firefox and enjoy your favorite, old extensions again :)”

    and it works like a charm. thanks a lot. u r the man!

    I just did one change. I downloaded the latest auto copy version 0.8!

  2. jean.phi |  Jun 20, 2008 at 10:21 am

    Thank you ! AutoCopy is my favourite Firefox extension and I was desperately waiting for an update.

  3. dostro |  Jun 21, 2008 at 7:21 am

    Hey guys!
    Firstly i want to say thankyou for the endeavor of the author which help me to use old extensions in FF3.
    However, this method does not work with me :(. Although i already followed all the above steps exactly, the result i’ve got is just a window reporting that autocopy does not provide secure updates (i did create and set the value of extensions.checkUpdateSecurity to false).
    Anyone can help me?

  4. dostro |  Jun 21, 2008 at 8:16 am

    Ok! I did it :D
    Thank you and sorry for my mistake

  5. Sun |  Jun 21, 2008 at 3:39 pm

    I am glad it works out fine for everybody. This is just a temporary solution, though. Hope we will get the update soon.

  6. Stuart |  Jul 02, 2008 at 1:32 pm

    a new version is out that works with ff3

  7. john |  Jul 02, 2008 at 3:11 pm

    i cant install auto copy because it says it is incompatible with ff3

  8. Blazko |  May 20, 2009 at 8:43 am

    Thanks for this hint!
    I just installed an old and forgotten EndNote plugin into FF3.

    Thanks again!