iMac 2013 will not install upgrade
I have downloaded the upgrade from 10.12.6 to 10.13 three times and each time the computer restarts, nothing has changed. It simply refuses to install and gives me no clue as to the reason why. I am on a late 2013 27" iMac with 24 gb of memory. The one possible cause is the continuing glitch in the OS that continue to reload my LaCie external drive used as TimeMachine, even though I have ejected it.
iMac (27-inch, Late 2013), iOS 8.1.2