Can't Put My iMac To Sleep

[scoostraw]

This is odd. I'm not talking about it going to sleep on its own after x-amount of time. I'm just clicking on Apple > Sleep. The screen goes dark but the system stays up. Always worked fine in the past.

I am on an older iMac running El Capitan. All of the threads I found addressing sleep issues seem to be with regard to a system waking up on its own.

This is different. Anyway, thank you if you have any ideas.

 

[chscag]

Try perfoming a SMC reset. The reset is easy for an iMac. Shut the iMac down completely, pull the AC cord from the wall socket, and let the machine set that way for a while. Then plug it back in and boot it up. You might have to do that several times. When I had a problem with my iMac (same thing, would not sleep) I had to shut it down completely overnight after several tries. Finally got it to work. That was with an older iMac I had and no longer have.

 

[scoostraw]

I should have posted this sooner. I just tried it and it went to sleep. First time in 2 days.

Thanks for the SMC reset tip. We did have a power outage here yesterday that lasted for about an hour. But it still would not sleep after that.

If it does it again I'll try what you suggested.