I was going to take Sunday off.
I woke up this morning and, by happenstance, decided to open Accumoo on my wife’s new iPhone 18 Pro, running iOS 27.2.
The splash screen appeared, and the app immediately crashed.
My wife wasn’t concerned about the data she had in Accumoo, so with her agreement, I uninstalled and reinstalled it.
Tried again. Crashed again.
So much for Sunday off.
Cartoon illustration; the affected phone was running iOS 27.2.
Nothing in Sentry
I checked Sentry. No crash reports.
The app had just crashed twice in front of me, but there was nothing there to investigate. I pulled the logs from her iPhone and asked Codex what the heck was going on.
The device’s native crash report pointed to UIKit’s scene-lifecycle adoption check. This was happening during native startup, before Accumoo could get to its normal screens.
An early startup failure could explain Sentry’s silence, but we haven’t verified exactly why it wasn’t reported. The crash report on the phone gave us something concrete to work with.
The problem was in native startup
Accumoo was still using an older native startup setup. Apple requires apps built with the latest SDK to adopt the scene-based lifecycle on iOS 27; apps that don’t adopt it fail to launch. Accumoo’s release records showed it had been built with the iOS 27.1 SDK.
This was a compatibility problem in Accumoo that I needed to fix.
The repair moves window creation and React Native startup into a scene delegate, while preserving deep links and foreground/background handling. Adding a scene declaration alone wouldn’t be enough: the app still needs to create its window and start React Native in the right place.
The change also lives in an Expo config plugin, so regenerating the native project retains the repair. I don’t want the next prebuild to quietly put the old startup code back.
To check the diagnosis, a small native test app reproduced the same UIKit launch failure when scene adoption was removed. With the scene setup in place, its lifecycle checks passed. The full repaired Accumoo build also reached sign-in on iOS 27.0 and iOS 26.5 simulators, including checks of actual deep-link routing on iOS 27.0.
Where things stand
A separate development build now opens on my wife’s phone, too. The hotfix hasn’t shipped.
The remaining work includes qualifying the signed production build, testing an upgrade with existing user data and offline changes, and checking notification taps and the widget/Watch package. Getting the app open is an important step; it doesn’t finish the release checks.
The morning I hoped to have off became a morning of crash logs, native startup code, and test builds. A casual decision to open my app turned into work I couldn’t reasonably leave for Monday.
It never ends. Apparently, that includes Sunday.