Heads up folks....
Apple released Mac OS X Sierra. Do NOT upgrade to it as it has not been approved by Avid at this time.
This is the follow-up to "El Capitan" and called "Sierra" (v10.12.0). The initial public release is scheduled for today 9/20/16
If you value your ability to operate Media Composer...
#1 DO NOT update your OS yet. Not until Avid makes a version of MC that can run on it. No version of MC running right now will operate on Sierra... Ever. Not MC8.x, MC7.x, MC6.5.x or whatever. You will need to download a new version (or patch upgrade) of Media Composer, qualified for Sierra, once Avid makes it.
#2 Sierra will be the first version since OS X Mountain Lion, released in 2012, that DOES NOT RUN on all computers that the previous version supported. So in a few months if you DO want to run a version of Media Composer that gets approved for Sierra, you may have to buy a new computer to do so.
#3: Even though you shouldn't install Sierra, you SHOULD download it for later. (Just don't install it.) Otherwise if you need the first release (10.12.0), you'll have it handy.
Avid's engineers and app designers are aware of Sierra. They have been working with Apple on a beta version of it, so that they can bring everyone a next version of Media Composer that will run on it.
But at this very moment while they are doing so, Apple is also making last-minute changes to Sierra for its release... and those changes may indeed affect all of the work Avid has done. Thus Avid will need to test their next version of MC on the SAME version available to the public, starting today.
Marianna