My brand-new M4 Mac mini arrived two days ago. It came with macOS Sequoia 15.1.1, and I updated it to Sequoia 15.2. This morning, at 6 AM, in my very cold home-office room (4 degree Celcius, 39 Fahrenheit) I pressed the Control key to wake up the sleeping Mac mini.
The Lock Screen displayed my account name and the password input field. I started typing my login password… but nothing happened. Looks like any text input (from the keyboard) is ignored! However, if I press the Return key, then the password entry field shakes, indicating wrong passwprd entry - of course, no text was entered yet.
That means, the keyboard itself was recognized (the Return key works) but normal character keys are not. Mouse is recognized and works perfectly on the Lock Screen. The result: I cannot enter my login password, and cannot log in.
My way out: I then used the mouse to select the “guest” account (which does not require a login password) and logged in there, opened Notes app to confirm that I can enter text normally, and then logged out from there and tried to log into my normal account. This time, it accepted my login password without any problem. Problem solved!
I called Apple Support. They said they have not heard of this kind of incident, but pointed out to me that the minimum operating temperature is 10 degree Celcius, 50 Fahrenheit.
I have been using iMac in this office room for years, and have never experienced this kind of problem. In winter morning in Kyoto, 4 degree Celcius room temperature is not uncommon.
Maybe Mac mini’s diminutive body makes it more susceptible to low temperature compared with iMac?
Could some keys on the keyboard be sensitive to temperature?
Is this the same keyboard you used with the iMac?
The iMac would certainly have been warmer than the mini, since it used more power.
However, if the mini is unresponsive because it is cold, I would expect the hardware to shut down and not operate any software at all.
What changed by logging in to the “guest” account to solve the problem?
Did the keys become warmer through typing on them?
Could some keys on the keyboard be sensitive to temperature?
I tried all alphabetical keys “a” to “z”. None worked.
Is this the same keyboard you used with the iMac?
Yes.
What changed by logging in to the “guest” account to solve the problem?
Simply because no password was set for the “guest” account. There was no need to type any password at all, so I was able to log into the “guest” account without using the keyboard.
Did the keys become warmer through typing on them?
When I started working at 6 AM, the room temperature was very cold, but since I switched the air conditioner (heat pump) the temperature went up, and it was certainly above 10 Celcius when I tried switching from the"guest" account.
I thought these moderate low temperature restrictions mostly had to do with risk of condensation on the electrical parts. But I have no idea if a keyboard can sensitive to low temperatures. If a key gets stuck the behaviour of the keyboard can be similar to what you are describing. Since it is a new keyboard I would suspect some kind of malfunction of the new keyboard rather than the Mac. Did a re-start help?
I am impressed by you working at 4 degrees room temperature… (and I live in Sweden so the conditions should not be that different but luckily I don’t have to work in that cold conditions). By the way, Kyoto is a very nice city.
But I have no idea if a keyboard can sensitive to low temperatures.
If a key gets stuck the behaviour of the keyboard can be similar to
I don’t think it is a problem in the keyboard. This particular keyboard has been working flawlessly for me for years. The thing that’s new is the new M4 Mac mini.
Since it is a new keyboard I would suspect some kind of malfunction
of the new keyboard rather than the Mac.
This is not a new keyboard. I have been using this since Mac Pro of early 2010s (I think), and I decided to continue using it when I bought a 27-inch iMac in 2018, because I disliked the flat-looking keyboard that came with the iMac. This is the thick-keytop Apple Extended Keyboard of 2010s, and it has never caused any problem for me. (except the “a” “u” “i” “o” key tops are all unreadable now)
I am impressed by you working at 4 degrees room temperature…
It is just the “first thing in the morning” stuff. I come into the room, wake my Mac from sleep, turn the air conditioner (heat pump) on, make a cup of coffee, sit down and start working, at which time the room temperature is over 10 degrees (probably 15 degrees or so.)
I wonder if your practice of turning the heat pump on and off might be involved. When we installed a heat pump for the whole house a couple of years ago, the techs said heat pumps are most effective if you maintain the same temperature all day long, because they need more energy to warm up than to maintain temperature. If it got well below freezing overnight in your office, frost might have formed somewhere inside the Mini. Did you check the humidity?
Another possibility that strikes me is the Mini might have had a glitch of some kind that delayed or prevented waking up from sleep. I have seen this on occasion both in my my 2018 Mini and my 2017 MacBook Air. This morning I couldn’t get the Mini to recognize the keyboard, which turned out to be caused by Word freezing.
A third possibility is that the keyboard might be wearing out, which I’ve seen happen after long use. If this happens repeatedly, you could try a different keyboard.
39F !! It must be difficult to type wearing mittens.
Please try with another keyboard if you can, as electronics age their thermal tolerances change. Usually this is manifested in heat related problems but hey why not cold, too.
Meanwhile I have a Mac mini running at our summer house (it’s mostly a media server - I usually turn it off by now but I guess I forgot), it regularly gets well below freezing in there, and that thing just chugs along with no problem. The keyboard and mouse are old USB wired ones and though I haven’t used it lately - I generally use it from screen sharing, even when I am there - I prefer them as it would be hard to get to them to charge them if they were Bluetooth.
I just checked, it’s 36°F in the house right now. It was as low as 15° on December 15 though.
Is the keyboard wired or wireless? I’ve had wireless keyboards not be connected on boot up causing this kind of problem, though the Return key working seems to indicate this is not the issue. I’ve solved it by plugging the keyboard in directly.
As an aside not finding the wireless keyboard on boot up seems to be an issue that Apple ought to address. Some years ago I was unable to log in to a brand new iMac that came with a wireless keyboard because of this. I’m guessing there must be a technological reason for this because I’ve had the issue continue over multiple generations of Macs.
My guess is that there was a crash or software glitch in the keyboard’s on-board controller. When you logged in to the guest account, macOS reset it, which made it all work again.
I suspect (but clearly can’t prove) that if you manually reset the keyboard (unplug/replug it if USB, or power-cycle it if Bluetooth), then that would have also worked. If the problem happens again, please give this a try and let us know if it worked.
… in addition to all the useful suggestions provided here by others.
When I saw the problem, I tried three (3) different keyboards (one wireless, USB) but the situation did not change. With all of the three keyboards, the Return key worked, and the alphabetical keys all failed to function.
But anyway, after some time passed, the room temperature went up, and the problem went away, as I’ve reported.
This morning, the room temperature was 6 Celcius (rather than yesterday’s 4 Celcius) and the problem did not occur.
Temperature sensitivity is absolutely an issue, and isn’t new to the M4 line. My 2019 Intel mini routinely loses wifi capability after a few hours in the modest ambient warmth of a UK summer; I was hoping moving up to an M4 might see the back of that, but should probably now temper my expectations.
It might not be the Mac. In Sydney (34C Forcast today!) I find my router wifi sometimes becomes patchy on hot days. According to the specs the router should work at much higher temperatures than our house but that is not my experience. Running Wifi Explorer on a Mac reveals the wifi dropping out for several seconds.
In my particular case it’s definitely the mini rather than the router; other devices continue to connect during the dropouts, which can be tamed by sleeping the mini for a bit. I’m running three displays off it, so it runs hot anyway, and it seems the summer heat is enough to tip it over the edge. It’s only the wifi that seems to be affected.
Since I have reported the problem on Dec. 28th 2024 (21 days ago), The problem re-appeared to me two more times. In both occurrences, the room temperature was lower than 5 degree Celsius (41 Fahrenheit).
The problem: My brand-new M4 Mac mini, macOS 15.2. In the winter morning, the room temperature is very low when I come into the home-office room. I try to wake up the Mac, but although the Control and Return keys on the keyboard are recognized, but alphabetical keys are not, and so I cannot enter my login password, leaving the Mac unable to wake up from sleep.
I have seen this situation three times, including this morning. However, in all of the three occurrences, the solution was simple:
Turn the heat pump on,
and wait for the room temperature to go up.
Once the room temperature goes above 10 Celsius (50 Fahrenheit) everything starts working - I can type my login password and wake up my Mac mini.
As I said, this problem is completely new with this M4 Mac mini (never occurred with my previous iMac,) and switching keyboards (wireless or USB-wired) didn’t change the situation. So the likely cause is the low room temperature, and Apple’s statement that the Mac mini’s “operation temperature” is 10-35 Celsius (50-95 Fahrenheit.) Three (3) occurrences is not a good sampling, though.
The recent article sprang to mind when reading through the thread. Sounds like the USB ports are lemons, but it’s unlikely Apple will recall or initiate a fix programme. Instead they will silently fix it for future units.
Anyway, are there multiple ports? Does using a hub between the Mac mini and keyboard help?
On the plus side, winter doesn’t last forever. But it does happen every year
I have been experimenting different USB ports, and it happens to be that the three (3) incidents occurred with Apple Keyboard connected to three (3) different USB ports on the M4 Mac mini.
So it looks unlikely that the USB port itself is bad. Furthermore, this morning, when I first tried to log into the “guest” account (which doesn’t require a login password,) I was successfully logged in there (but the alphabetical keys still didn’t work) but an alert appeared, saying it is “not connected to the Internet” suggesting that the Gigabit Ethernet port was bad, too.
As I said, once the room temperature went up, all keys on the keyboard started working, and Internet connection was working fine.
On the plus side, winter doesn’t last forever. But it does happen every year
Oh sure. :-)
I would be just happy if this could help in some way for Apple to fix a problem for future units.
I’m beginning to sound like a stuck record, but have you tried disabling sleep? M-Series Macs use so little power that sleep mode is just pointless and it might be that the small amount of heat is enough to make the machine happy. You can activate a hot corner to put the display to sleep but the Mac will continue running.
