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Nighttime Power Cycling Bug Afflicts iPhones and iPads

Reports are making the rounds about a bug in iOS 17 and iPadOS 17 that causes devices to shut off at night and restart in the morning. The giveaway is being asked for your passcode because the iPhone or iPad has restarted. For confirmation, check Settings > Battery > Last 24 Hours, which will show a gap if the device was dead to the world overnight.

Doug Miller broached the topic on TidBITS Talk, sharing screenshots from his iPhone and iPad, both of which decided to shut down for hours on the same night. Notice that the iPhone screenshot on the left has a pause icon and lacks the green background and lightning bolt of the iPad screenshot that indicates charging. But the graph shows that the iPhone must have been charging because it’s fully charged when it restarts around 7 AM. 

iPhone and iPad battery graphs showing shutdown at night

My iPhone suffered the same problem the next day, but my screenshot looks like Doug’s iPad screenshot in terms of icon and background, so it doesn’t add anything new. In contrast, Dana Schwartz posted a screenshot that shows the pause icon and white background along with the comment, “Charging was on hold due to iPhone temperature.” Dana said the iPhone was sitting bedside charging, just like every other night, so there’s no external reason it should have overheated. Notice that when the graph resumes, the battery level is higher than before the pause but not fully charged. The differences suggest that the bug may have multiple triggers or effects depending on other variables.

iPhone temperature-related shutdown?

It’s odd that the bug hit so many people in the last week, and while most were running iOS 17.0.3, plenty were still using earlier versions of iOS 17, and one person experienced it with the developer beta of iOS 17.1. A very few people claim they’ve seen it in earlier versions of iOS, but such reports are exceptions.

For many people, these restarts aren’t all that problematic. I mostly don’t care what my iPhone does or doesn’t do while I’m asleep as long as it’s fully charged and ready to use when I wake up. However, some have missed alarms, and calls that would have woken you up could be lost. If you have a can’t-miss alarm for an early morning flight or essential meeting, set a backup on another device until Apple addresses the bug. We hope that happens soon.

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Comments About Nighttime Power Cycling Bug Afflicts iPhones and iPads

Notable Replies

  1. Dang. When I noticed I had to put in a password in the morning, I just had assumed it was some sort of restart from an automatic update.

    However, it looks like the phone in the chart was off for hours.

    Then again, if the phone was off, why did it automatically turn itself back on after a few hours? That one actually is a bit more disconcerting to me.

  2. Apple hasn’t commented on this issue yet as far as I know, so we don’t know for sure why it happened (or has been happening for those who have multiple incidents.) WE also don’t know if the device was powered off or if there was some other bug. I will say this: when I picked up the phone and removed the lightning adapter it was showing the Lock Screen as usual, but asking for the passcode rather than unlocking with Face ID. There was no delay that might be expected if the phone was powered off, so it may have been powered on the whole time. The iPad was the same. It’s still only happened that one time to me. both iPhone and iPad, on the same night, on October 10.

  3. In my case, I’ve been able to tell that the iPhone has restarted (or at least logged off) because I have Weather widgets on my lock screen and they were blank. So, the request for the passcode was not the random request that you get when you have not entered it in a while.

  4. I’ve experienced this on my iPad on iPadOS 16 irregularly but repeatedly since I bought it earlier this year, usually about once every two to three weeks. Since the iPad literally isn’t doing anything when I’m not actively using it, this isn’t a big deal, though it did once happen while I was playing a game on it; that annoyed me greatly. The telltale, as with the iOS/iPadOS 17 bug, is the request for a passcode that mentions “after your device has restarted”.

    Fortunately, it hasn’t happened to my iPhone yet. I’m going to hold off on updating to iOS 17 until we learn more about this bug, and maybe until Apple fixes it.

  5. I’ve had this happen on my iPhone for years.
    I have the auto-update feature disabled, so it is not iOS system updates.
    I know it is from a restart because I’ve gotten the password required “after your device has restarted” message.
    I always assumed it was a system crash or something, but found it odd that it happened overnight, while my phone was very stable during the day.
    I’m glad this is getting more attention. It will be very interesting to find out what in the world is going on.

  6. Maybe the message “after your device has restarted” is misleading and this isn’t a restart but some other system operation that requires a passcode?
    I think I also needed to enter a passcode last week. I also needed to sign out of iCloud and back in on my iPad to get several serices working.
    It will be creepy if Apple (or another agent?!) is able to do this remotely. Didn’t it happen around the time that Apple issued a security update:

    Or is that just my normal paranoia? :sunglasses:

  7. There definitely are other times that iOS will ask for your passcode, and it’s certainly reasonable to think that the bug is just in which message we’re seeing, not that the phone has actually restarted. This morning, the message I saw was “a shortcut will run after you phone is unlocked”, I needed to type my passcode and there is a gap (with a charging icon). iOS will also regularly ask for your password at intervals simply so you don’t forget what it is (usually the message at that point is something like “you need to enter your passcode every [time period]” - and I think the time period varies depending on a few factors). The message I see most often is “you need to enter your passcode to enable faceid” - many of these messages don’t give you any idea whether the phone restarted or not. I always just assumed it was the remember-your-password interval, but it’s been going on for years.

    I think there may be some jumping to conclusions here - there’s no reason to think that the gap with the pause icon means the same thing as the gap with the charging icon, or even that the phone was “turned off” during that period. One could be an indicator of battery optimization, one might be an indicator of overheating - the only thing we can be absolutely sure of is that the messaging is unclear.

    And we can also be sure that some people are missing alarms - but that could be an entirely separate or tangentially related bug.

  8. I’ll just add that I have checked each morning since last week and I still haven’t seen the pause icon, on either device. And it happened to enough people on one specific day (October 10), and, I think, specifically on iOS and iPadOS 17.0.3, that 9to5mac wrote an article about it. What happened to my phone and iPad, at least, was an anomaly, and perhaps different from anything that’s being reported with the overheating message.

  9. If you read the passcode prompt carefully, it will actually reveal that it is not just the “random” every 6th day request. The prompt spells out that a passcode is needed since the iPhone was restarted. AT least that is exactly how it showed on my wife’s 15. Twice now already.

    It’s not just thinking it restarted. The iPhone did restart. It’s revealed in the battery/charging history. It’s clearly a bug, but there is no doubt the iPhone was not operational during the pause.

  10. I wish this were just another “minor annoyance” as another user put it, but I am an ICU physician and I am on call at night. I need my phone to be on and able to receive calls!

  11. So this whole issue has really piqued my interest. I was unaware of it until yesterday when I read it on TidBits. This morning I was asked to enter my passcode. I went into settings and noticed the gap in the battery graph as has been described. So I guess my phone was off. But was it really? Or is the bug in the way that the battery usage is reported? I woke up in the middle of the night during the purported “phone off” period and touched the screen to check the time. The phone was on. Now I’m really confused.

  12. The pause sign indicates charging is paused at 80% due to you selecting optimized charging (or in sokme cases overtemp). If you experience this actual bug, you don’t just get a pause icon, you get a shaded area with missing charge state bars during that period in spite of the flash symbol below. See @ace’s screen shot above.

  13. Yes the graph indicates that the phone was off however it wasn’t as I checked the time. It had to be on.

  14. I use my iPhone as my Nightstand clock with an app during the night. I expect that clock to be on all night long. last night I woke up to find the New sleep screen clock running. I’m not sure what woke me, but the sleep clock went away and I got the prompt to sign in with my password. When I touched the screen, the password request went away, and my Nightstand clock app appeared. That does not make any sense. I’m running iOS 17.0.3.

  15. I have an iPhone SE, 2nd Generation running iOS 16.7.1.
    When I did that last security upgrade, my phone started dimming at odd times, usually late afternoon. It did not turn off, but I haven’t (checked the settings, soft reset) been able fix this. Also, sometimes, again in afternoon or early evening, it gets hot when I’m using it. So turn off and do something else for awhile. This may or may not occur at same time as the dimming. So wondering if the larger problem is somehow related to one of the security issues/fixes.

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