My iMac does not sleep after install of El Capitan

Resetting the printing system did the trick for me as well

Thank you! Worked for my late 2012 iMac.

SOLUZIONE

Salve a tuttt,

Ho risolto il problema dello spegnimento del Mac( xkè anche se si spegneva il Sistema e lo schermo di El Capitan 10.11.4, il Computer continuava ad andare):

Soluzione!!:

Installare Kext 'CPU POWER MANAGEMENT' in LIBRARY e dovrebbe sparire il Difetto , e in circa 30'' sec. si spegne del tutto!!

Ciao.

I just noticed my 2015 iMac 5K is not sleeping when idle. I am running 10.11.4 GM. pmset indicates “Idle sleep preventers: IODisplayWrangler.” I will try resetting the printing system as suggested.

My one (macbook pro 13" with retina) has the same problem. it never goes to sleep when i closes the lid. pmset indicates “Idle sleep preventers: IODisplayWrangler.” And I think this problem caused the logic board failure a few weeks ago, which cost me AUD900 to replace a new one.

I should get refund if that's a bug of EI Capitan. :-(

I think it always indicates “Idle sleep preventers: IODisplayWrangler.” If there are assertions preventing idle sleep, it will have a value other than zero for PreventUserIdleSystemSleep and list the process(es) preventing sleep under “Listed by owning process.”

It kind of sounds like yours thinks it is in clamshell mode, but I could not find where to check that.

Resetting the printing system as described in an earlier post worked in my case.

Okay, there was PreventUserIdleSystemSleep=1, it became 0 after I did "resetting printing system". It's ridiculous to pay AU$900 if the logic board failure was caused by a "never-sleep" bug. I know I don't have any evidence to say the bug caused the failure, but it could, right? I think Apple should launch a re-call scheme for it.

Anyway I will shut it down every time before I put it into my backpack, can't trust them any more, hopeless!

I was having the same problem, something keeping the iMac from going to sleep, display sleeps fine but hard disk keeps spinning and mouse LED stays on. Apple support offered some suggestions in the following post:

OS X El Capitan: If your Mac won’t go to or stay in sleep

I tried everything they suggested: Checked system’s sleep settings; system’s network access settings; system’s Bluetooth settings; system’s sharing preferences; Unexpected keyboard presses or mouse and trackpad clicks; Apps that access a disk; Spotlight indexing; Connected storage and devices, etc. I even went through the trouble of resetting SMC, PRAM, and deleting the power management plist. Nothing. Then I tried the ultimate trick, a clean install of OS X but to no avail. I even made sure the clean install was done without restoring the user's preference files so that system settings would revert to default. Then, reading this post I discovered that many people were having success by resetting the printing system which got me thinking that maybe, just maybe, there was a print job stuck in the printer's queue that was keeping the computer from sleeping because I normally keep my printer off. Sure enough, once the stuck print job was cancelled problem resolved !!! To check the status of the print queue: System Preferences > Printers and Scanners > Open Print Queue

Now, looking at the statistics in this post, most people were able to resolve this issue by resetting the print system, however, I suspect that in many cases the original issue may have been a stuck print job which probably gets cleared by resetting the print system. NOW HOW COULD APPLE MISS THIS LITTLE BUT IMPORTANT CHECK IN THEIR SUGGESTIONS ABOVE !?! It is kind of stupid if you ask me, that a stuck print job should keep a computer from sleeping for days, weeks, months, years unless it's cleared ! NOT EVEN A CLEAN INSTALL OF THE OS COULD CHANGE THAT !!! I mean comm'on programmers, if the job is stuck for DAYS why isn't the OS smart enough to figure out that it's no longer needed, cancel the print job automatically and go back to normal operation. UNBELIEVABLE !!! Also, APPLE PROGRAMMERS: if you're monitoring these posts, please add a print status indicator to the menu bar so that we know this is happening. Also, to anyone else reading through this post, if I can offer some advice, turn of Spotlight indexing because it will consume clock cycles like it's going out of style and will also keep your computer from sleeping, all for so little benefit in return. Won't go into details of how that's done here as there are other posts on the subject. In my opinion Spotlight is one of the dumbest and most useless features ever implemented by Apple in their computers.

And don't feel bad if this happened to you also, I've been using apple computers since 1986.

Thanks for the tip.

My MacBookPro9,1 had the same issue after upgrading from OS X 10.9.5 to OS X 10.11.4

It was sleeping when on battery but when plugged in it would not sleep.

Resetting the printing system fixed this so will sleep as normal.

Hi.

I had the same problem, OSX El Capitan, energy saver did not work after installing X-Plane 10, it ignored any settings. After a couple of day research I found out that the problem was not the software, but the joystick connected to a USB port!. If I disconnect the joystick, energy saver works well. Maybe this could be helpful. Regards.

same problem in Sierra

the print services repair fixed it for me!!! THANKS!!