Intent to deprecate: MacOS 10.6-10.8 support

Benjamin Smedberg benjamin at
Thu Mar 10 18:03:43 UTC 2016

This is notice of an intent to deprecate support within Firefox for the 
following old versions of MacOS: 10.6, 10.7, and 10.8

The motivation for this change is that we have continued failures that 
are specific to these old operating systems and don't have the resources 
on engineering teams to prioritize these bugs. Especially with the 
deployment of e10s we're seeing intermittent and permanently failures on 
MacOS 10.6 that we are not seeing elsewhere. We get very little testing 
of old MacOS versions from our prerelease testers and cannot dedicate 
much paid staff testing support to these platforms. We also have an 
increasingly fragile set of old hardware that supports automated tests 
on 10.6 and do not intend to replace this.

This will affect approximately 1.2% of our current release population. 
Here are the specific breakdowns by OS version:


The final timeframe for this deprecation has not been finalized, but the 
current proposal is to remove support in Firefox 46. We will try and 
update existing users on old MacOS versions to the Firefox 45 ESR 
release stream, so that they stay with security update support through 
the end of 2016.

Because of the ESR update window, I would like to finalize this decision 
by Monday. If you have questions or concerns about this plan, please 
reply to the firefox-dev mailing list immediately. Jeff Griffiths will 
be working with our communications team to coordinate more public 
communications such as post to the Future of Firefox blog.


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