iPhone reboot screen apple logo

If you’re one of those jailbreak users that have been plagued with random reboots of your iPhone when plugged in at night, then we might have a fix for you. As explained by Reddit user TuttoVaBene, those reboots seem to happen as your iPhone exceeds a certain memory limit. While there is no clear explanation of what really happens or why, it appears that manually increasing the memory limit can fix the problem.

As TuttoVaBene details on Reddit, if you go to Settings > Privacy > Diagnostics & Usage > Diagnostics & Usage Data on your iPhone, you might find an entry for SystemMemoryReset, which shows that the system memory limit was exceeded, causing the unfortunate event.

As you can see on this screenshot, the memory limit was set to 225 MB, but 375.33 MB was needed, which caused the device to reboot.

TuttoVaBene explains that raising the memory limit can prevent this issue. He suggests maxing out the limit to match the total memory available on your device, which I think might be overkill, but you be the ultimate judge.

How to increase the memory limit

Before we move forward, I must include a disclaimer to completely release my liability should something go wrong. You’re obviously doing this at your own risks, understanding that you could mess things up. If you’re fine with that, then go ahead. If you’re in doubt, I suggest you just stay away from this fix.

It is also unclear what side effects this might have on your device. Going through all the comments in this Reddit thread, I didn’t find one person that encountered an issue, but this is the kind of “fix” that could cause problems that go unnoticed for a while and hit you when you least expect it.

So again, proceed with caution.

1) Download a file manager such as iFile or Filza in Cydia.

2) Open the file manager, in our case, we are using Filza, and navigate to /System/Library/LaunchDaemons/com.apple.jetsamproperties.NXX.plist. You may see two similar files named the same, with one containing the letter “m” after the device internal model name. For example, here we have a file ending in N71.plist and one ending in N71m.plist.

launch daemons

3) Tap on the first file and locate the UserHighWaterMark by going to Root > Version4 > System > Override > Global > UserHighWaterMark. The default value is set at 225 on my device.

UserHighWaterMark default

4) Tap on UserHighWaterMark and edit the value. I set mine to 600, and you may set yours to whatever you want but make sure it doesn’t go over the amount of memory available on your device. For example, if you have 2GB of RAM on your iPhone, don’t set the value over 2048 (MB). Tap Back, then tap Save and Done.

UserHighWaterMark edit

5) Repeat the process for the other file, if you do have that file on your device.

I just went through the process myself and it’s pretty straightforward. While it’s obviously too early to tell whether that did it or not, many users or Reddit and a handful of iDB readers are reporting that implementing this has fixed the random reboots at night.

If you do decide to implement this fix, let us know how it went.

Source: Reddit via @MikeDeezy100

  • dnice

    ill just wait until i tweak is released, which i would imagine wont be long.

    • Dodgy Debjit

      Don’t hold your breath – this “fix” has been out for over 6 months.

  • Y2J

    I’m really starting to miss having a jailbreak

  • f96lrs

    Jailbreak is dead

    • Diego Milano

      I wouldn’t call it “dead” but it may certainly very well be the case for the latest iOS iteration, unless any of the hackers want to burn exploits that may very well be safe to keep in the event they still exist in iOS 10.
      That being said, however, it’s undeniable that tweak development has decreased considerably in the 6-12 months, which is a bit depressing as stock iOS has A LOT of space for improvement. 🙁

    • Jayy

      Yeah it’s really not dead. But in all honesty I believe only the people who have been waiting for a jailbreak say that it’s dead, and the people who are Jailbroken right now like myself have no complaints.

      • f96lrs

        I am on 902 JB no problems but they can sell there exploits

  • Bugs Bunnay

    I have a very good explanation for this! Tweaks with leaking memory, sloppy coding, and tweaks that don’t play nicely with one another!

    • Like you, I originally believed this was due to bad tweaks, but the problem is that this also happens on non jail broken devices, so your theory doesn’t really work anymore.

      • Bugs Bunnay

        hmm. one more theory could be that the iPhone doesn’t like night time and so it freaks out. someone have a night light and report in the morning!

      • MSiqueira

        I suspect this happens for a long time. But it refuses to talk to me about it..

      • Diego Milano

        The article doesn’t specify on what iOS versions this is happening. I’ve NEVER experienced this in any of my devices in the past 7 years or so, that I remember, and never with any iOS 8 not iOS 9 iteration.
        It’s worth to mention that I’m on iOS 9.0.2 at the moment, but since the “fix” has been around for more than 6 months, it’s safe to assume that the issue sprung up at least on early versions of iOS 9.

      • Tim

        I’m on iOS 9.0.2 and I have been having this issue. Since the manually fix it clearly stopped.

      • Diego Milano

        What device do you have it running on? I’m on iPhone 6s Plus here.

      • Tim

        This was on iPhone 5.

      • 919263

        Happening on my iPad Air2 with NO JB… so it is not related to JBing…

  • BAiNZy3

    This conflicts with your previous article on the matter, where it explained that it is was down to the Touch ID ‘countdown’… is it both, the latter or the above article?

  • diggitydang

    Changed my 6s to 512 yesterday and the reboot happened again overnight, so I’m not so confident in this theory! Tried bumping it up to 1024 – we’ll see what happens…

    • Raul Torres

      Did bumping up to 1024 fix it? I set it to 600 still roboots.

      • diggitydang

        Yup, set mine to 1024 and it appears to work great. Good luck!

  • 7000rpm