How do I resolve battery drain and performance issues after iOS 27 update on iPhone 17 Pro?

FidaMuhammad1 wrote:

i am facing problem with my 17 pro after Ios27. The phone is not smooth as last update. Charging is draining fast.

[Re-Titled by Moderator]

Original Title: iOS 27 issue

The first thing I do after EVERY iOS update is Force Restart my iPhone. Have you done this --> Force restart iPhone - Apple Support

For the last step where you press and KEEP HOLDING the side power button, do NOT let go of the button until you see the Apple Logo. KEEP HOLDING it even when you see the swipe to power off and KEEP HOLDING when the screen goes black and KEEP HOLDING it until you see the Apple Logo, then let go.

Something that might help with battery on iOS 27: turn off Connectivity Assist. It's Wi-Fi Assist with a new name and a new spot in Settings.

When your Wi-Fi gets weak or stops loading, your phone jumps over to cellular to keep things working, then jumps back. On spotty Wi-Fi it can do that over and over. All that back and forth keeps the cellular radio busy, and that drains the battery.

You have to turn it off in two places. First, go to Settings > Wi-Fi, scroll down to Connectivity Assist, and turn it off. Then tap the little (i) next to the network you're on, scroll down to Connectivity Assist again, and turn that one off too.

That second step is the one people miss. I turned off the main switch and it was still on for my home network.

Welcome and thank you for reaching out. 🤗

A rapid battery drain after updating to iOS 27 can happen while the system reindexes and optimizes in the background, usually taking a day or two.

According to Apple: If you notice that your battery life has decreased after updating your device, wait a few days and then check again. Even though you can use your device immediately after an update, certain tasks related to the update continue in the background and might affect battery life and thermal performance. While they're ongoing, you might see the Insight Ongoing iOS Update in Settings ➢ Battery.

If you need more help, contact Apple Support directly.

Take care!

Smiliñ 😎 Brian | Community Volunteer

It is going to take 4-5 days, possibly more for everything on the iPhone to be indexed. During this time, the battery is working very hard.

You should notice an improvement after a week or so.

Your iPhone has a lot of work to do right after an iOS update. It redoes preparations for Spotlight searches, for example.

Battery use will subside after a while.

battery life has dropped a lot after installing IOS 27, this was installed a few days back

I am going on 5 days now, nothing but factory apps, brand new Iphone 18 Pro, was fully updated and already had 27.0.1 installed.

iPhone 18 Pro battery drains quickly with… - Apple Community