I'm trying to learn what is preventing my install of Firefox from using multi-process functionality (also called "Electrolysis" or "e10s"). Mozilla's wiki gives instructions on how to force enable multi-process windows and I have already changed browser.tabs.remote.autostart and browser.tabs.remote.force-enable to 'true'.

Checking about:support I see the message "Multiprocess Windows 0/1 (Disabled by add-ons)"

about:support screenshot

However this message persists even after restarting Firefox with all add-ons disabled. I have taken the additional step of checking arewee10syet.com and if the data on that site is correct, all my extensions are compatible already.

How can I troubleshoot this further, and discover what is preventing me from enabling this feature?


The Ubuntu Modifications add-on is blocking multiprocess windows:


To disable it: In about:addons click on the Extensions category, find the Ubuntu Modifications add-on and click its Disable button. Restart Firefox and then go to about:support. The status of Multiprocess Windows should now read "1/1 (Enabled by user)".

  • I tried this early on, however the duplicate bug listed mentions extensions.e10sBlockedByAddons which I had accidentally left set to 'true', and resetting it to the default fixed the problem. Simple user error, and I'll close the question. Thanks for the help, this pointed me in the right direction. – Tom Brossman Apr 24 '17 at 5:19

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