After upgrading to Sierra I'm having issues. Appls & external drives are locked up after the iMac comes out of sleep mode. Can't even perform normal shutdown. After reinstalling OS a second time still get the same result. Upgraded from El Capitan. My iMac is a Retina 5K, 27-inch, Late 2015 with 2TB internal hard drive & 3.3 GHz Intel Core I5 processor.
iMac, Mac OS X (10.7.3), null
I had similar problems in reverse. My 27 inch iMac would freeze most days requiring powering off and on, and waking from sleep was problematic. Apple's advice for problem identification was not practical. Upgraded to Sierra and during the process (forgot why) I unticked the Put Hard Disk to Sleep when Possible in Energy saver and leave ticked prevent computer from sleeping when screen blanks. The combination of the unticking part hard disk to sleep and Sierra has given me four freeze free days (my record is nine so not celebrating yet) but waking is no longer a problem. Might as well try that and see how ti works.
Thanks for your reply. I tried the same thing but got no improvement. Have given up and reloaded El Capitan. Took a lot of time to get everything aligned with that OS. Never ran into an issue with upgrading before, very disappointed!
I resolved my problem by going back and ensuring that I had the latest updates to all my appls specifically including 3rd party appls which were not identified by the Appl Store.
Having problems after upgrading to Sierra.
