iOS18，CoreText EXC_BREAKPOINT

Can you provide more information about, say, the code that is running when you see this exception?

I'm also having this issue, coming from production app, we are not able to reproduce. The only thing we know is that it's from CoreText and here TDecorationRun::CalculateGlyphIntersections.

It's very specific to some users, about 50, but we already have 500 crash events for those 50 unique users.

Can you provide a complete crash log? Or a listing of the code that you suspect is running at the time of the crash?

Hello,

We don't have specific points of the app code where it may be crashing, since it's random, we already seen code crashing at very different locations around the app. Currently, about 5% of our users base is having this crash, also another detail, we are seeing this around different versions of iOS, not specific to iOS 18 or 26. We suspected at first about the compiler of new Xcode 26 (since this was the first version compiled with new Xcode), but it seems it is not that. We have sent a new build out today, compiled with Xcode 16.4, but no luck, still crashes.

I'm attaching 2 screenshots, from the crashing stacktrace, one from Sentry and the other one from Xcode crash reporter directly. Also, attached the .crash file with the full stacktrace that can be found at Xcode.

Thanks for the crash log. This doesn't appear to be Core Text related. It looks more like it's related to a CATransaction being processed in the main loop. In these cases I usually suggest looking for some other thread that is trying to do something that may simultaneously access something that Core Animation is using - even something as simple as accessing a property since that can potentially run code.

@DTS Engineer we have been able to detect the crash issue. It's happening indeed on rendering of an UIButton, and not something related to CATransaction or race conditions between threads.

The issue happens when using a parenthesys as part of text in a button title, that is using a custom font (Uniform-Medium) and we have the Acessibility option Button Shapes enabled. If we do remove the parenthesys, as we did in order to fix the crash for our users - it works normally.

We have created a demo app here, it's hosted on GitHub, and it has more information on the README file. But basically running the demostration app with the accessibility option Button Shapes enabled it's enough to see the crash happening.

Thank you for your attention.

Hi @leokaminski07. Thanks for posting a sample project. I was able to reproduce your results here using your sample on an iPad Pro running iOS 26.0.1. Beyond turning off the Button Shapes option, I don't have any recommendations for avoiding this bug.

Our engineering teams need to investigate this issue, as resolution may involve changes to Apple's software. Please file a bug report, include a reference to your Xcode project and post the Feedback number here once you do. If you post the Feedback number here I'll check the status next time I do a sweep of forums posts where I've suggested bug reports.

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