Firefox for Mac Sandbox Info

As of version 52, Firefox made a change that restricts the internals of the browser from accessing certain areas of the file system. Unfortunately, when MySpeed tries to work with Firefox, these restrictions can (not always) cause a Firefox tab to crash.  Your screen may look like this below.    

If you haven't done so yet, download MySpeed 6.4 (6440) and read the updates below.




The technical term for the restriction is a ‘sandbox’. MySpeed needs to use and create some files in the file system in order to work; we place these files in a safe location, and are attempting to work with Mozilla to create an exception for these files. Firefox tabs are usually contained within a process called the ‘plugin-container’, which is why there is a separate checkbox preference for that. This is the process Firefox most often uses to play the web content in a tab, and the process with the most restrictions on accessing the file system as part of the Firefox sandbox. MySpeed preferences allow you to choose what works best for you; for instance, you can just disable MySpeed from working with the Firefox Plugin Container:


MySpeed works with Firefox with plugin-container OFF



However, it is very likely (though not always) that MySpeed will not be able to change the speed of audio/video content in this configuration.
If you wish, you can disable the Firefox sandbox using MySpeed Advanced Preferences or during installation (you can re-enable later as well) by checking the Firefox’s Plugin Container checkbox in MySpeed Preferences. If the Firefox sandbox is enabled at its default level, MySpeed will help you disable the Firefox sandbox so you can continue to enjoy web content at your own speed:
If you ever decide that you wish to restore the Firefox sandbox to its default level, just uncheck the Firefox’s Plugin Container checkbox and MySpeed will help you to do just that. 
Preferences screen shot if you need that.

How to disable the sand box manually

  • In MySpeed, go to preferences and turn off the Firefox Plugin Container.
  • Close Preferences
  • Start Firefox
  • Go to about:config
  • Click "I accept the risk!" button (as shown below)


  • Type in browser.tabs.remote.autostart in the Search bar (as shown below)


  • Double Click browser.tabs.remote.autostart and browser.tabs.remote.autostart.2
    so the value column changes for each of them to false and now looks like this:


  • Now you can re-enable the Firefox Plugin Container in MySpeed Preferences