notamused.org

Many Firefox add-ons are not yet updated to support Firefox3, even though they probably work fine anyway. You could try bypassing the extension compatibility check by following this guide. This is not recommended as it may break your installation of Firefox, but it worked fine for me.

1. Start at Firefox’s address bar and type this in:
   about:config
2. Right click anywhere in the list and select New then Boolean
3. Enter extensions.checkCompatibility when it prompts you for a preference name.
4. Select False for the boolean value.

You have just told Firefox not to check extension compatibility. Now cross your fingers, restart Firefox, and hope for the best!

First make sure you have the Adobe Flash plugin installed. It is not packaged with any version of Firefox.

$ sudo update-flashplugin
$ sudo apt-get install flashplugin-nonfree

This package of flashplugin-nonfree was made before the Firefox3 pre-releases, so we have to add it to the libraries manually. This method will “link” it from the default install location (not just copy it) so in case you upgrade flashplugin-nonfree in the future, it will be updated for Firefox3 as well.

$ sudo ln -s /usr/lib/firefox/plugins/flashplugin-alternative.so /usr/lib/firefox-3.0b3/plugins/flashplugin-alternative.so

If you are using a different version of Firefox3 than I am (firefox3.0b3) you’ll need to modify that line. To test if it worked go to a flash site such as YouTube.com.