iMac 27" 5K - Turning Off


macrumors newbie
Original poster
Jul 12, 2009

I have upgraded to the latest OS Mojave and ever since I have done this my iMac turns off and does not go to sleep.

I always leave my machine on and now when I return I have to turn it on at the back instead of just pressing a key and then putting in the password.

Does anyone know what could have changed.

Many thanks in advance.



macrumors regular
Jun 29, 2007
Metro Detroit
I had a similar issue, not with Mojave, but an app that was installed was causing a system hang and it was crashing. Check the console app in utilities. Searching the log just before it shut down might reveal something.


macrumors 68000
Jul 24, 2007
Troutdale, OR
My 27” 2017 iMac is currently at Apple getting serviced for this very issue. Fortunately Apple was able to reproduce it, the local store is working with Apple corporate (according to the tech I directly talked with) to figure out which components to replace.

This web site helped me, I had several zero status shutdowns logged, despite using an apc ups system and being asleep when they occurred.

I used the terminal command in Mojave listed on that web page, then looked up the codes (5 is normal, zero is power interruption).

Fyi, my iMac was doing this on both high Sierra and Mojave’s.
Last edited:


macrumors 68000
Jul 24, 2007
Troutdale, OR
For what it is worth, Apple was able to reproduce it once, but they called it a display failure, but for some reason they are now insisting an macOS reinstall has fixed the problem.

I am going to pick up the computer the next couple of days and hopefully it is actually fixed, but I am not confident in their fix at all.

I will bring it into Apple again should the problem reoccur.
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