[Sentry: APP-H7A] Fabric removeViewAt crashes removing view from non-ViewGroup parent #103369

Sentry

https://expensify.sentry.io/issues/APP-H7A — IllegalStateException: Unable to remove a view from a view that is not a ViewGroup

Impact (snapshot at filing, 2026-10-07)

• Users (total since first seen): 109
• Events: 114
• Users (last 14d): 21
• First seen: 2026-07-07
• Last seen: now (ongoing)
• Platform: Android, HybridApp (org.me.mobiexpensifyg)
• App version(s): 9.4.31 through 9.5.1-1, including every build after the APP-7AR fix (9.4.93-3, 9.4.94-0, 9.4.99-2, 9.5.0-5, 9.5.1-1)
• Affected route(s) (parameterized): n/a — native Fabric mounting, not a JS route
• Mechanism: UncaughtExceptionHandler, level fatal

Stack trace (top frames, first-party only)

com.facebook.react.fabric.mounting.SurfaceMountingManager.removeViewAt(SurfaceMountingManager.kt:445)
com.facebook.react.fabric.mounting.mountitems.IntBufferBatchMountItem.execute(IntBufferBatchMountItem.kt:125)
com.facebook.react.fabric.mounting.MountItemDispatcher.executeOrEnqueue(MountItemDispatcher.kt:379)
com.facebook.react.fabric.mounting.MountItemDispatcher.dispatchMountItems(MountItemDispatcher.kt:250)
com.facebook.react.fabric.FabricUIManager$DispatchUIFrameCallback.doFrameGuarded(FabricUIManager.java:1664)

Error: IllegalStateException: Unable to remove a view from a view that is not a ViewGroup. ParentTag: N - Tag: M - Index: K

Suspected cause

SurfaceMountingManager.removeViewAt finds a ViewState for the parent tag, but its view is null or not a ViewGroup, and it throws (v0.86.0 source). The likely source is the same as APP-K0G: updateEventEmitter creates a placeholder ViewState with no view for a tag Java no longer has, or a differ flatten/unflatten bug leaves a stale parent.

This is not the APP-7AR root cause. Fix Android Fabric mount crashes from merged mounting transactions dropped APP-7AR to near zero, but APP-H7A kept its rate: 24 events in the 14 days before 9.4.93-3, 18 in the 13 days after.

Upstream already handles this case. react-native@3f553d7 replaces the throw with a soft exception, because a non-ViewGroup holds no children and the remove is a no-op. That commit landed after 0.86.0. A backport as a new RN patch should stop the crash, the same way #102901 handles addViewAt for APP-K0G.

Reproduction

Unknown — see Sentry events linked from the Sentry issue. Most users hit it once, which fits a timing race in mount batches.

Related

• Sibling Sentry IDs: APP-K0G, the addViewAt twin ([$175] [Sentry: APP-K0G] Fabric addViewAt crashes adding view into non-ViewGroup)
• Prior GH issues: [Sentry: APP-7AR / APP-H7A] HybridApp Android Fabric mount crash (filed APP-H7A together with APP-7AR; APP-7AR is fixed)
• Parent tracker: [Tracking] Top Sentry crashes monthly check-in #91302