Level 1

31 points

Apple Watch Ultra 4 randomly restarts

Hi everyone,

I'm having a frustrating issue with my Apple Watch Ultra 4 (European version). It just randomly restarts itself throughout the day.

I'm on the latest update. The restarts are completely random and happen no matter what I'm doing – the screen just goes black, the Apple logo pops up, and the watch reboots.

I've already tried the standard fixes I found online:

Hard reset (holding the Digital Crown and side button).
Unpairing and setting it up as a completely new watch (without restoring from a backup).
Deleting third-party apps and turning off Background App Refresh.

None of this helped. Are any of you guys experiencing this issue on the latest software, or did I just get a defective unit? Any advice before I contact Apple Support for a replacement?

Posted on Sep 19, 2026 12:32 PM

Top-ranking reply

TuMiDaj Author

Level 1

31 points

Posted on Sep 20, 2026 1:20 PM

Thanks for the reply! You were right to suggest contacting Apple, as it seems I've exhausted all software troubleshooting.

I decided to dig into the Analytics Data on my paired iPhone and actually found a full Kernel Panic log corresponding to the exact time of the latest crash. It points directly to a hardware/firmware timeout issue with the Apple Neural Engine (ANE).

Here is the specific panic string from the log:

panic(cpu 1 caller 0xfffffff04b12bfd8): "ANE0: ANEHWDevice::ANE Timeout: channel=DataChainingCommand cmd=0x020C (CSNE_CMD_PROCEDURE_CALL_WITH_CUSTOM_BARS), waited=2020 ms, timeout=2000 ms, fANEFirmwareEnablePanicOnTimeout=1 unitTestMode=0\n" @ANEFirmwareManager.cpp:2974

And the faulty kext in the backtrace is: com.apple.driver.AppleH16ANEInterface

Has anyone else seen this specific ANE timeout panic before? I will definitely show this to Apple Support to speed up the diagnostic process, as it strongly suggests a defect with the Neural Engine chip rather than a rogue background app. I'll update the thread once it's resolved and I get a replacement.

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31 replies

tom5640

Level 1

4 points

Sep 21, 2026 3:46 AM in response to TuMiDaj

Just +1ing this. Doesn’t seem to be any particular function that causes it. I’ll see the screen blank and think it’s gone to sleep and then all of a sudden after a few more seconds the Apple logo. Since having watch on Friday it’s happening 1-2 times daily.

TuMiDaj Author

Level 1

31 points

Sep 21, 2026 8:39 AM in response to TuMiDaj

Right now, the biggest mystery for me is whether this is an actual hardware defect or just a software bug. If it's a hardware issue, I'm planning to return it immediately. Since I bought it online in the EU, I have a statutory 14-day return window no questions asked, and I'll definitely use it.

Has anyone found any concrete info or official acknowledgement on what exactly is causing this? On the other hand, if it's strictly a software issue, I really don't mind waiting for the next watchOS update. I just don't want to risk the return window closing and ending up stuck with a defective unit.

wilce

Level 1

8 points

Sep 21, 2026 9:06 AM in response to wilce

Five times now! And that is after chatting with Apple Support and unpairing and repairing the watch. Like everyone else, I’d like to know if it is a software or a hardware issue. Planning to use the watch and the mapping for a weekend hiking trip in a couple of weeks. Should I return it for a replacement or hope for a software fix before then?

Sep 21, 2026 9:57 AM in response to Jeff Donald

Neither Apple or Apple Support will confirm. It’s just not how Apple prefers to operate with potential customer service issues.

It's like your auto insurance company says, if you're in an accident, do not admit fault. Resist the urge to even say, "I'm sorry" as that can be taken as admission of fault.

That's probably why Apple will not say anything. They'll patch the problem and re-iterate "this fixes a reboot issue experienced by a small number of users" as they always do.

Sep 21, 2026 1:16 PM in response to TuMiDaj

Me too! I got my watch from Canada to get pulse ox saturation right on the wrist (I live in the US) and my Ultra 4 keeps doing the same thing! It did it twice during my spin class and I was very frustrated

diz-nutz

Level 1

12 points

Sep 21, 2026 6:52 PM in response to TuMiDaj

Everything seemed alright Friday and Saturday however, the restarts started yesterday (09/20/2026) with my ultra 4. It has restarted about four times and Siri wouldn’t respond randomly until actually opening the Siri app on the watch. I will be contacting Apple if it happens again for a third straight day.

Sep 20, 2026 4:09 PM in response to TuMiDaj

on my Apple Watch 4 Natural Titanium it's only when i'm texting someone on iMessage, now i'm with a tech online they run a diagnostic on it everything is good no issues

Sep 20, 2026 8:20 PM in response to TuMiDaj

I am also having similar kind of issues my ultra 4 watch had rebooted 6times in last 2 days!

Sep 20, 2026 9:33 PM in response to TuMiDaj

I have series 12 and have the same reboot issue.

wilce

Level 1

8 points

Sep 21, 2026 12:06 AM in response to TuMiDaj

I’m having exactly the same issue with similar looking panic logs. Four times in four days

Steveps3

Level 1

78 points

Sep 21, 2026 8:14 AM in response to Jeff Donald

No need to return it. It’s happening to a lot of watches. Looks like a software glitch. Apple will come out with a fix shortly. Getting another one means you will probably have the same issue.

dorin165

Level 1

8 points

Sep 21, 2026 8:52 AM in response to TuMiDaj

Same issue here, it happened four times today. Apple Watch Ultra 4. I’m waiting for a reply from the Apple expert. I hope it’s a software issue, which could be solved via an update.

Sep 21, 2026 8:58 AM in response to TuMiDaj

Not Ultra 4, but considering purchasing. I currently own an Apple Ultra(1). However, I’m a former Apple Store manager and occasionally have insights on how things work and can help with expectations.

Sep 21, 2026 9:09 AM in response to wilce

Extremely unlikely a fix would happen before Friday, September 25.

Tattynut

Level 1

8 points

Sep 23, 2026 9:41 AM in response to TuMiDaj

Same error for me - just SAD!

better get a garmin ya‘ll

Apple Watch Ultra 4 randomly restarts