IOS 26.1 is a big problem for my older IPhone 12. My battery repeatedly went from 85% charge to nothing and the iPhone spontaneously shuts off during a brief phone call. The log contains the error “update finish took too long since supply finish event” and I assume I have to do a restore from my MacBook or is there a way to delete the installed update killing my iPhone?
iPhone 8, iOS 16
I am surprised....amazed really.....that you were even able to install iOS 26 with the Battery Health in that condition.
That battery should have been replaced 8-12 months ago.
Make an appointment at the Apple Store / Genius Bar or take the phone to an authorized Apple service shop if that would be more convenient. (It often is).
You can find a list of authorized shops in your area using this link:
Estimate $90-100 (U.S).
I am surprised....amazed really.....that you were even able to install iOS 26 with the Battery Health in that condition.
That battery should have been replaced 8-12 months ago.
Make an appointment at the Apple Store / Genius Bar or take the phone to an authorized Apple service shop if that would be more convenient. (It often is).
You can find a list of authorized shops in your area using this link:
Estimate $90-100 (U.S).
The log contains the error “update finish took too long since supply finish event”...
— Do you have a pending update?
— Do you know what the update might have been?
— What does Settings > General > Software Update show?
Connect the phone to its charger and see if the update completes.
My battery repeatedly went from 85% charge to nothing
When I had a battery fail prematurely in an iPad, I had the same symptoms and my "health" was far better than yours at the time. Runtime from fully charged to zero was 12-13 minutes
lagreb21 wrote:
It’s degraded 71% and I know it needs replacing but my careful treatment kept it functioning until IOS 26
Batteries that depleted can start to swell. This can cause damage to the phone, including popping the screen off. If that happens, you'll be looking at a lot more money to fix it than just replacing the battery.
What is the Maximum Capacity of your iPhone 12's battery?
Settings > Battery > Battery Health & Charging > Maximum Capacity
It’s degraded 71% and I know it needs replacing but my careful treatment kept it functioning until IOS 26
I’m sorry, I must not have answered you correctly. My battery is degraded—71% max. But I didn’t have any problems until IOS 26.1.
Another point. Batteries for iPhones older than the 15 series are rated for only 500 cycles, not 1000. Starting with the 15 series, full size phones had 1000-cycle batteries. The fact that your 500-cycle battery went this long is an achievement, not a bug.
Ref: MacTracker database: https://apps.apple.com/us/app/mactracker/id430255202?mt=12
For comparison, we have two SE 2020s bought new on 2 Nov 2021 with 500-cycle batteries. One now has 560 cycles and 81% health and the other 440 cycles and 83% health. Both still deliver plenty of runtime for our needs.
IOS 26.1 error depletes battery
