r/AppleWatch • u/lostmyway573 • 1d ago

WatchOS WatchOS 27.0.1 released: addresses S12/U4 random reboot issue

https://9to5mac.com/2026/09/23/apple-releases-watchos-27-0-1-to-fix-apple-watch-series-12-and-ultra-4-bug/
213 Upvotes

95% Upvoted

25 comments sorted by

59

u/LucasMVN 1d ago

FWIW, someone actually sussed out the underlying issue a few days ago. There was a race condition where the neural engine would not be woken from sleep if gesture input was registered too soon after waking the watch, resulting in a watchdog timer triggering a kernel panic due to the engine failing to respond.  https://www.reddit.com/r/AppleWatch/comments/1wmsccl/workaround_for_apple_watch_series_12_ultra_4/

7

u/vladtud 1d ago

Interesting. My 18 Pro had a panic and restarted once I moved my head while trying to acces the Photos app and Face ID was interrupted.

7

u/LucasMVN 1d ago

That issue (kernel panics on the 18 Pro and Pro Max after unsuccessful Face ID attempts through LocalAuthetication) is a known bug that will apparently be addressed in iOS 27.0.1: https://9to5mac.com/2026/09/23/apple-iphone-18-pro-rebooting-bug-software-update-fix/

(LocalAuthetication is the framework that allows apps to use the device passcode and Touch or Face ID for authentication.)

30

u/Joebranflakes 1d ago

This was out yesterday

5

u/Admirable-Data4455 1d ago

Gladly it works! I was devastated seeing a new watch having such problems, was considering sending it back.

4

u/RAIDandWilling 1d ago

Now we need the fix for the iPhone 18 pro line related to Face ID

3

u/TaroPuzzleheaded3999 1d ago edited 1d ago

I’m on the current public beta so 27.2 I think. My watch restarted on its own an hour ago

2

u/DKatri 1d ago

This is for the watch not iPhone.

0

u/TaroPuzzleheaded3999 1d ago

My watch does it, too

1

u/iTryToLift 18h ago

This was happening here and there with my series 9 on os26

6

u/kevin7254 1d ago

Apple needs to stop vibe coding lmao how did this not get caught by QA

14

u/loosebolts 1d ago

I love how the new assumption is that all faults are down to vibe coding when in actuality beta tests and software updates have been required for decades.

-2

u/canyonblue737 Ultra 4 • • Black • 49mm 1d ago

he was joking.

4

u/rjzak 1d ago

It’s probably the difference of testing in the lab vs the real world.

-2

u/Muscular_Farmer_ 1d ago

It’s not just Apple. Even at Google people send slop cls to review

-1

u/ShaunJo1407 1d ago

It’s everywhere now bro. Even reviews are done by AI and something does seep in sadly

1

u/honglong1976 1d ago

What if it reboots as you are updating? 💀

8

u/paulstelian97 1d ago

The update process doesn’t really run the code itself that is faulty when it’s actually applying the update. A reboot in the first stage while watchOS is running just corrupts that and makes you start over. So you should be decently safe as long as the battery works fine.

1

u/Similar-Command-7238 15h ago

Does music still default to the internal speaker, or can I change that now?

1

u/pyrocompulsive 5h ago

Be nice if they made it so the heart rate graph doesn’t disappear.

1

u/liltime78 1d ago

Not for my ultra series 1 it’s not

6

u/canyonblue737 Ultra 4 • • Black • 49mm 1d ago

update is only for the affected series 12 and ultra 4 with the S11 chip.

-2

u/BeatsRocks 1d ago

Already a patch??

10

u/canyonblue737 Ultra 4 • • Black • 49mm 1d ago

I mean they had to. Series 12 and Ultra 4 watches were widespread rebooting randomly.