The title says it all. I upgraded to 12.3 and now my monitor will not wake from sleep. I have to reboot the Mac mini to get the monitor working. I'm not alone -- a thread on Reddit is discussing the same issue.
Apple, why do monitors continue to be a problem? MacOS 12 has had a steady stream of monitor-related issues since it's launch.
Answer: Change your cable from "standard" to "high speed" - see below for explanation.
There are loads of articles on the net saying that their external monitor stopped being recognised after a software upgrade ("No Signal" error showing on the monitor).
There are so many upgrades to the operating system these days, it seems like anything which goes wrong can be blamed on the latest OS upgrade. Probably a fair chunk of new problems are indeed due to upgrades. Some might be other causes.
In my case I think it was a combination of two causes.
1) The software upgrade, AND
2) The cable that I was using to connect the Mac (an iMac Pro) to the external monitor (a Samsung S27D590).
The monitor has a maximum resolution of 1080p.
I tried a lot of things, especially fiddling around with the settings in Apple logo>>System Settings, Displays, and in Desktop & Screensaver. Restarting the Mac sometimes worked.
After a lot of fiddling around, I came to the theory that the problem might have something to do with the cable connecting the the two devices (USB-C to HDMI).
Initially I found the one way to resolve the problem was to disconnect the USB-C to HDMI cable and then re-connect it. - Very irritating fix! Finally I changed the USB-C to HDMI cable for a new one. The problem has not occurred since I did that.
In conclusion, I think the problem was that the cable connecting the monitor to the Mac wasn't working with the latest software upgrade on startup.
Why did changing the cable work?
Answer 1: Cable Quality: There are loads of "inferior quality" cables, particularly ones bought cheaply from China. Such cheaper cables are more likely to suffer from a poor connection issue (e.g. a loose or broken strand of wire inside the cable, or the connecting ends). Also the wires may not be pure copper. To save money, the manufacturer may have used an amalgam of copper and aluminium, resulting in signal loss - especially for longer cables.
Answer 2: If you bought a cheaper cable, or if you bought it a long time ago, it is unlikely to be up to the latest standards.
Cables are grouped into one of four categories, standard, high-speed, premium high-speed, and ultra-high-speed. Standard is the slowest of all the cable types at around 4.9 Gbps. Normally this should suffice to handle 1080p but not much else. Given that newish Macs can output signals at much higher resolution than 1080p, it is possible that the latest software attempts to start out in the the higher resolution mode. A "standard" cable can't handle that, and therefore can't report back that the monitor is only 1080p.
Nowadays, most shops only sell "High-Speed" cables or higher. These HDMI cables will support at least double the bandwidth of a standard cable and can handle 4K video with ease. If you buy a new cable from a reputable shop, and check the specification is "high-speed", or "ultra-high-speed", you should be fine. In other words, do not buy the cheapest cable.
Mac Mini 2018 working fine here with Dell 3219Q monitor and 12.3. Wakes from sleep just fine. Using Thunderbolt to DP adapter and connecting to DP input.
I’m sorry but seems to me that you’re adding Samsung to this problem on-the-fly when in fact your issue is with LG. Samsungs may well have issues too but as of now I haven’t seen an original, credible discussion mentioning them in the first instance as having this issue.
In any case, confirmation that LGs have the problem is enough. It’s either a newly-introduced bug or newly-introduced fix to a long-standing security hole for 3rd monitors that aren’t fully compliant with Apple’s requirement for unique ID.
Only time will tell, all the best.
Just because YOU haven’t seen any discussions about other monitor brands, doesn’t mean they don’t exist:
https://forums.macrumors.com/threads/monterey-12-3-beta-broke-second-display.2332775/post-30938696
https://forums.macrumors.com/threads/monterey-12-3-beta-broke-second-display.2332775/post-30937616
And who decides when a discussion is "original" and "credible"?
I wrote “seems to me” = IMO = in my opinion. I stand by it, not interested in macrumors. In case you didn’t know, a rumor is neither original nor credible https://www.merriam-webster.com/dictionary/rumor…thanks anyways 😁
I wrote “seems to me” = IMO = in my opinion
No, you didn't.
"but as of now I haven’t seen an original, credible discussion mentioning them in the first instance as having this issue."
Instead of losing yourself in pointless semantics discussions, you could try to be helpful. Or silent.
If you discredit user experiences, just because the forum they posted them in is hosted by a website with "rumor" in its name, you appear to be biased and driven by your own agenda. Let me guess, you wouldn't believe something by 9to5mac either, because you're not interested in normal business hours.
You seem very determined to lay the blame solely at LG's feet and acquit Apple from any wrongdoing, when other brands are also concerned and all these monitors worked fine before 12.3.
Which post are you referring to? Mine was to my last response to DVMagicStudios after which you jumped in. It’s there in the very first sentence. And yes, I’m only responding to user experiences on this site. Based on it, only LGs are exhibiting this issue because their implementation is suspect. Links from other discussion forums/I heard it on the internet…hmm, maybe silence is the best answer 😁
hcsitas wrote:
Which post are you referring to? Mine was to my last response to DVMagicStudios after which you jumped in. It’s there in the very first sentence. And yes, I’m only responding to user experiences on this site. Based on it, only LGs are exhibiting this issue because their implementation is suspect. Links from other discussion forums/I heard it on the internet…hmm, maybe silence is the best answer 😁
Just not true. You responded to a post clearly stating that Samsungs are affected, too.
DVMagicStudios wrote:
I had swapped out my LG’s with pair of Samsung tonight from another Mac still on 12.1, same issue.
hcsitas wrote:
I’m sorry but seems to me that you’re adding Samsung to this problem on-the-fly when in fact your issue is with LG. Samsungs may well have issues too but as of now I haven’t seen an original, credible discussion mentioning them in the first instance as having this issue.
I do understand your frustration, but there’s nothing in your reply it that contradicts my post or gives me pause. So, it stands as written including this bit: “All the best.” I hope you and others find a resolution soon. Good luck! Keep us posted.
You just responded to another thread where in the two posts before yours the users clearly state that they have the same problems with Samsung and BenQ monitors. In this thread, a user clearly states that the problem occurs with his 2 Samsung monitors.
[Edited by Moderator]
@DVMagicStudios: I just wanted to say thanks for your very comprehensive and helpful posts on this issue. I have been experiencing exactly the same problems since the 12.3 release; but sadly don't have sufficient spare equipment at my location to try any real troubleshooting. As a result, it's been incredibly valuable to be able to read your reports. Please keep the info coming! I suspect this will end up being something that Apple will have to address directly in a future software update; but you might just stumble across a workaround that would help us all in the interim.
--&e
This was a thoughtful suggestion but did not resolve the issue. I thought you might want to know that if I turn my computer on before the monitor is on, it will not display and provide a no signal error.
I have updated to 12.3.1 now for several weeks and this problem is NOT FIXED. I have a 2020 Mac and I think this problem started happening since I upgraded to 12.3.1 or 12.3.
My mac doesn't have to be connected to a monitor or using any external mouse or keyboard. Just typing any key on the laptop does not wake my laptop from sleep (laptop monitor remains dark). Even typing the esc-key or power key (not holding down since I don't want a reboot) several times does not wake my mac up from sleep. It takes about a minute of pressing various keys for it to finally wake up.
My power setting is set all options off except "Wake for network access" and "Enable Power Nap while plugged into power adapter" on.
Is there some one to contact Apple to let them know that what they claim to have fixed in 12.3.1 wasn't really fixed?
Sure, but this issue did not exist in 12.2.1.
It isn't just about sleep mode. Third party displays don't work with 12.3.
That’s too sweeping to take seriously.
Monitor not waking from sleep after 12.3 upgrade
