Firefox 4 Beta 7 breaks Flash on Mac - Solution

Updated: November 27, 2010

Here's a simple, possibly quite common scenario for you: you are a Mac OSX user and you have decided to download and install the latest Firefox 4 beta version on your machine. All is well, except that your Flash plugin no longer works. The following attempts to fix the problem do not yield any positive results: reinstalling Flash, enabling and disabling the Flash plugin or even using a new profile. What do you do now?

This is the problem my brother faced on his Mac machines with the latest Firefox beta, at version number 7 at the time this article was written. No doubt the problem will be officially resolved in the future, but for now, enjoy not one but two solutions. Screenshots and all the hard detective work, courtesy of my brother. Now read on, fellas.


Affected platforms

The problem may affect you on 64-bit Mac OSX 10.6.5 and 10.6.4 and possibly lower versions, too. If you're not seeing this problem, you can safely ignore this article, but be aware of the fact things may break down the road, especially if you're using beta software.

Force Firefox to start in 32-bit mode

To do this on Mac, go to HD > Applications > Firefox > right click or Control click > Get Info.

Get info

Now, tick the checkbox that reads Open in 32-bit mode.

32-bit 132-bit 2

Disable hardware acceleration

A second method is to disable hardware acceleration. Go to Preferences > Advanced. On the General tab, untick the checkbox that reads Use hardware acceleration when available.

Disable HW acceleration


Restart Firefox and enjoy Flash once again.


There's nothing much to say except remind everyone that beta software is beta for a reason. Using non-officially released software could lead to problems, crashes or even a loss of data. Just be aware of this subtle yet critical truth and you should be fine.

This short tutorial offers you two different workarounds to the Flash Player functionality on Mac OSX. I hope you liked them. Stay tuned for any updates. That would be all, mates.