iPhone 12 Pro Max randomly restarts and has volume issues after iOS 27 update

If your battery health is 50% this is most likely the culprit. Apple advises a replacement of the battery with 80% health so yours is long due.

You can also try and force restart it to see if the issues persist, but I advise a battery replacement anytime soon

1. Press and quickly release the volume up button.
2. Press and quickly release the volume down button.
3. Press and hold the side button.
4. When the Apple logo appears, release the side button.

cmorhead wrote:

I had done the force restart, that didn't help. I just forced all oustanding app updates, incase it was a rouge app causing the problem. The problem still persists.

What I need help understanding is why my phone was stable while the battery health was below 80% but above where it is now.

Once battery health dips to 80% or lower and in your case SIGNIFICANTLY LOWER, the battery is so depleted that it's a wonder your phone hasn't swelled or worse gone up in flames. Apple posted a notice in your iPhone that Battery Service was required when the health dipped to 80%. You ignored the notification and your phone is failing. I don't know what more explanation is required? iOS 27 put even more strain on a battery which was severely depleted. It's simply that simple.

You need to immediately schedule a battery replacement at your Apple Store Genius Bar or trade your phone in and get a new iPhone. This isn't a "when you get around to it" situation.

Apple Service and Repair for iPhone Battery - Apple Support

If you believe the issue you are experiencing is not related to your battery health being at 50%, then

You may try some of these steps. Please check after each step...

1. Having too many apps open may cause this issue, as RAM is being used by other apps, leaving less memory available for proper rendering. Close an app on your iPhone or iPod touch
2. Overloaded system: Too many apps running in the background can cause stuttering. Refresh content in apps you're not actively using on ...
3. Storage issues: Low or fragmented storage can slow down the camera. --> Manage and Clear Storage on your iPhone a… - Apple Community
4. Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.
   1. Restart the device. That's it.
   2. Still not solved --> Force restart iPhone - Apple Support
5. If you're using a VPN, disable it and check if the error goes away. Go to Settings > General > VPN & Device Management and turn off any active VPNs. Disabling a VPN only from the iPhone settings may not completely turn it off. To fully disable it, you need to switch it off from the VPN service provider’s app or remove the configuration profile they installed. Only then is the VPN truly off, which can help if it’s causing issues with cellular or Wi-Fi connectivity.
6. Reset Network Settings: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings: Only network settings are removed.
   1. When you reset network settings, previously used networks and VPN settings that weren’t installed by a configuration profile or mobile device management (MDM) are removed. Wi-Fi is turned off and then back on, disconnecting you from any network you’re on. The Wi-Fi and Ask to Join Networks settings remain turned on.
   2. To remove VPN settings installed by a configuration profile, go to Settings > General > Profiles & Device Management, select the configuration profile, then tap Remove Profile. This also removes other settings and accounts provided by the profile. See Install or remove configuration profiles on iPhone in this guide.
   3. To remove network settings installed by MDM, go to Settings > General > Profiles & Device Management, select the management, then tap Remove Management. This also removes other settings and certificates provided by MDM. See “Mobile device management (MDM)” in the iOS Deployment Reference.
   4. Reset your Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you've used before.
   5. 
7. If the issue persists, you can try resetting all settings on your iPhone. This will not erase your data but will reset all personalized settings to their default values. Go to Settings > General > Transfer & Reset > Reset > Reset All Settings and confirm the action. Note that you will need to reconfigure your settings afterward. All settings—including network settings, the keyboard dictionary, the Home screen layout, location settings, privacy settings, and Apple Pay cards—are removed or reset to their defaults. No data or media are deleted.
   1. Reset All Settings: Return iPhone settings to their defaults - Apple Support:- Return iPhone settings to their defaults
   2. You can return settings to their defaults without erasing your content.
   3. If you want to save your settings, back up your iPhone before returning them to their defaults. For example, if you’re trying to solve a problem but returning settings to their defaults doesn’t help, you might want to restore your previous settings from a backup.
   4. 
8. Make sure you have the latest updates installed.
   1. Update Over-the-Air (OTA) —> Update your iPhone or iPad - Apple Support (IN)
   2. Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)

If none of the above steps resolve the issue, it is recommended to reach out to Apple Support or visit an authorized service center for further assistance. They can provide specific guidance based on your device model and iOS version.

Hey I have the same problem with the same phone I didn't even update my phone to the new version its still a 26.6.1 iOS

my battery health is on 82% and it started after I dropped my phone not even that much it was in the car it felt on the floor of the car and it restarted a first time I even had to take it to the local phone repair shop because I couldn't get it started so they changed the Power Button & Volume

Button Flex Cable and I thought that would work and that's it but no after a few hours it started again and it is doing now I have the exact same problem with my phone and I don’t know what to do.

I had done the force restart, that didn't help. I just forced all oustanding app updates, incase it was a rouge app causing the problem. The problem still persists.

What I need help understanding is why my phone was stable while the battery health was below 80% but above where it is now.

cmorhead wrote:

I updated my iphone 12 pro max to iOS 27 and now it is randomly restarting.

Not every issue an individual encounters on their device can be attributed to an iOS update. iOS 27 or later may have coincided with what you are experiencing, but that does not mean the issue was triggered by iOS. Coincidence in timing is not, by itself, evidence of causation.

If the update itself were the root cause, then every device running that same version of iOS would exhibit the identical problem. In such a scenario, the forums would be flooded with countless posts reporting the same malfunction, creating an unmistakable wave of complaints that no one could possibly overlook.

The absence of such widespread reports strongly indicates that the issue is not a general, system-wide problem with iOS 27 or later, but rather something specific to the individual device, its configuration, installed apps, settings, hardware, or another interacting factor.

In short: iOS 27 or later may be a coincidence in timing, but there is no basis to conclude that iOS itself triggered the problem simply because the issue appeared after the update.

See what each update does: About iOS 27 Updates, About iOS 26 Updates, About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...