How do I resolve overheating, slow loading, and missing emails after updating to iOS 18.5?

After installing of 18.5 - major issues. Phone overheating. Loading taking a lot of time. Mail not showing up - have to restart.



[Re-Titled by Moderator]

Original Title: 18.5 issues

iPhone 12 Pro, iOS 18

Posted on Jun 10, 2025 1:57 AM

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Question marked as Top-ranking reply

Posted on Jun 10, 2025 9:36 AM

FIRST: Do you have a 3rd party VPN installed, even if you are not using it? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile. If that fixes it, you can try reinstalling VPN. 


Let’s define “overheating”, which is always a hardware problem. If a device overheats it shuts down so it can’t be used, and displays a message saying it must cool down before it can be turned on, and it will probably be unusable for an hour or so. If you are seeing this it is a hardware problem and you should contact Apple support: 

Note that both of the above have options to receive a callback or chat


If you are not seeing this your iPhone or iPad has not overheated. However, if you fast charge your device it may get very warm, and may pause charging at 80% and display a message saying that charging has paused, and will resume when the phone cools down. This is NOT overheating, and is normal when fast charging. It also won’t prevent you from using any app you have on your phone.


If you have just updated allow a couple of days for iOS to complete its “housekeeping"


Some apps that use a lot of energy or that use cellular data rather than Wi-Fi can cause the phone to run warmer. Worst offenders are Meta products (Facebook, WhatsApp, Instagram, etc), interactive games, watching streaming videos, and the Camera app. And having VPN installed, whether using it or not, can also consume a lot of energy.

All of these are manifestations of the 2nd Law of Thermodynamics.

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Question marked as Top-ranking reply

Jun 10, 2025 9:36 AM in response to MJDZ4

FIRST: Do you have a 3rd party VPN installed, even if you are not using it? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile. If that fixes it, you can try reinstalling VPN. 


Let’s define “overheating”, which is always a hardware problem. If a device overheats it shuts down so it can’t be used, and displays a message saying it must cool down before it can be turned on, and it will probably be unusable for an hour or so. If you are seeing this it is a hardware problem and you should contact Apple support: 

Note that both of the above have options to receive a callback or chat


If you are not seeing this your iPhone or iPad has not overheated. However, if you fast charge your device it may get very warm, and may pause charging at 80% and display a message saying that charging has paused, and will resume when the phone cools down. This is NOT overheating, and is normal when fast charging. It also won’t prevent you from using any app you have on your phone.


If you have just updated allow a couple of days for iOS to complete its “housekeeping"


Some apps that use a lot of energy or that use cellular data rather than Wi-Fi can cause the phone to run warmer. Worst offenders are Meta products (Facebook, WhatsApp, Instagram, etc), interactive games, watching streaming videos, and the Camera app. And having VPN installed, whether using it or not, can also consume a lot of energy.

All of these are manifestations of the 2nd Law of Thermodynamics.

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How do I resolve overheating, slow loading, and missing emails after updating to iOS 18.5?

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