Hi all! Like everyone else, I upgraded to Sierra. I'm running a 5K 27' iMac. Everything is actually perfectly fine for the most part. The only small issue I have is during reboot or shutdown. It'll display an odd graphical glitch for maybe a second, then shutdown or reboot perfectly fine. It only started after upgrading to Sierra...so I'm sure its a software issue. Here is what it looks like: http://wilparker.d.pr/BZ6F Any thoughts? I simply upgraded from El Cap to Sierra. I then tried a clean install followed by a restore from time machine. Still having same issues. Was wanting to prevent from starting "fresh" completely... blah. Anybody with a fresh install having this as well?