Screen not waking

Somewhere I read about a situation where a Mac’s screen goes to sleep and does not respond to any attempts to wake it, necessitating a forced restart. Apparently the computer itself is still functioning in other ways. Does this sound familiar? Does anyone know what to do about it? It happens to me several times a week.

If you’ve got an Intel Mac, try resetting the PRAM or NVRAM:

also, did you change the screensaver preference? or alternatively, delete
(in ~/Library/Preferences )

I usually experienced this with an external monitor in clamshell mode. Several iterations of sleeping/waking, unplugging/replugging screen, opening/closing lid most times eventually get it to wake. But it’s a pain. And it’s been going on for many macOS versions.

If this has been going on across many OS updates, reboots, PRAM resets and SMC resets, then it might be a hardware problem.

I remember (from various Louis Rossmann videos) that the Hall-effect sensor used to detect lid open/close events sometimes fails. The result is that the computer thinks the lid is always open or always closed, resulting in symptoms similar to what you’ve seen.

If it thinks the lid is always closed, the screen won’t turn on and the motherboard will ignore input from the trackpad (!).

This is a pretty straightforward repair for someone capable of doing board-level repairs. Apple, of course, will only fix it by swapping the motherboard, which is expensive and may be impossible if the computer is too old.

Well in my case this has happened on several of my MBPs so in all likelihood it’s not hardware. My money would be on shoddy code.

Thanks for many responses. Actually, I find this only on my iMac (late 2017); that’s the only one of my machines I leave running for any length of time. As I mentioned, I am pretty sure I have seen a reference to it somewhere, and guessed it would have been TidBITS. Maybe not. I have reset NVRAM and PRAM to try to get things to run cooler but that didn’t change this behavior. I have run Electric Sheep as a screen saver for a long time; I will try removing that from the mix.

Same here with my MacBook Pro 2012.

Update–the iMac is history and I don’t see any repetition of the problem on my new MacMini.