[Gamma Tabs] Crash: "FragmentManager is already executing transactions" in TabsContainer.updateSelectedFragment during Fragment.onResume

[tomekzaw]

Description

Our app received a crash report from Google Play Console on a release build using the new Gamma Tabs API (com.swmansion.rnscreens.gamma.tabs).

The crash is a java.lang.IllegalStateException: FragmentManager is already executing transactions, thrown from TabsContainer.updateSelectedFragment (TabsContainer.kt:563) when it calls commitNowAllowingStateLoss.

The root cause appears to be re-entrancy of the FragmentManager. The chain is:

1. FragmentManager is in the middle of dispatchResume / moveToState (an active fragment transaction is executing).
2. TabsScreenFragment.onResume (TabsScreenFragment.kt:28) fires emitOnDidAppear.
3. That onDidAppear event is dispatched synchronously to Reanimated (NodesManager.onEventDispatch → performOperationsRespectingDrawPass → FabricUIManager.scheduleMountItem), which synchronously flushes mount items while still inside the resume pass.
4. The flushed mount items reach TabsHost.didMountItems → TabsContainer.flushPendingUpdates → performContainerUpdate → performSelectedTabUpdate → updateSelectedFragment, which calls commitNowAllowingStateLoss.
5. Because a fragment transaction is already executing (step 1), ensureExecReady throws FragmentManager is already executing transactions.

So a synchronous tab/mount update is being committed re-entrantly from within Fragment.onResume, which the FragmentManager does not allow.

Expected: Pending tab updates committed during/triggered by a fragment lifecycle callback should be deferred (e.g. posted) rather than committed synchronously, so they never re-enter a FragmentManager that is already executing transactions.

Full stack trace

java.lang.RuntimeException
  at android.app.ActivityThread.performResumeActivity (ActivityThread.java:6269)
  at android.app.ActivityThread.handleResumeActivity (ActivityThread.java:6342)
  at android.app.servertransaction.ResumeActivityItem.execute (ResumeActivityItem.java:73)
  at android.app.servertransaction.ActivityTransactionItem.execute (ActivityTransactionItem.java:63)
  at android.app.servertransaction.TransactionExecutor.executeLifecycleItem (TransactionExecutor.java:169)
  at android.app.servertransaction.TransactionExecutor.executeTransactionItems (TransactionExecutor.java:101)
  at android.app.servertransaction.TransactionExecutor.execute (TransactionExecutor.java:80)
  at android.app.ActivityThread$H.handleMessage (ActivityThread.java:3150)
  at android.os.Handler.dispatchMessage (Handler.java:110)
  at android.os.Looper.loopOnce (Looper.java:273)
  at android.os.Looper.loop (Looper.java:363)
  at android.app.ActivityThread.main (ActivityThread.java:10060)
  at java.lang.reflect.Method.invoke
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:632)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:975)
Caused by java.lang.IllegalStateException: FragmentManager is already executing transactions
  at androidx.fragment.app.FragmentManager.ensureExecReady (FragmentManager.java:1947)
  at androidx.fragment.app.FragmentManager.execSingleAction (FragmentManager.java:1977)
  at androidx.fragment.app.BackStackRecord.commitNowAllowingStateLoss (BackStackRecord.java:323)
  at com.swmansion.rnscreens.gamma.tabs.container.TabsContainer.updateSelectedFragment (TabsContainer.kt:563)
  at com.swmansion.rnscreens.gamma.tabs.container.TabsContainer.onMenuItemSelected (TabsContainer.kt:602)
  at com.google.android.material.navigation.NavigationBarView$1.onMenuItemSelected (NavigationBarView.java:449)
  at androidx.appcompat.view.menu.MenuBuilder.dispatchMenuItemSelected (MenuBuilder.java:833)
  at androidx.appcompat.view.menu.MenuItemImpl.invoke (MenuItemImpl.java:157)
  at androidx.appcompat.view.menu.MenuBuilder.performItemAction (MenuBuilder.java:984)
  at com.google.android.material.navigation.NavigationBarView.setSelectedItemId (NavigationBarView.java:1037)
  at com.swmansion.rnscreens.gamma.tabs.container.CustomBottomNavigationView.setSelectedItemId (CustomBottomNavigationView.kt:32)
  at com.swmansion.rnscreens.gamma.tabs.container.CustomBottomNavigationView.setSelectedItemIdWithActionOrigin$react_native_screens_release (CustomBottomNavigationView.kt:22)
  at com.swmansion.rnscreens.gamma.tabs.container.TabsContainer.performSelectedTabUpdate (TabsContainer.kt:498)
  at com.swmansion.rnscreens.gamma.tabs.container.TabsContainer.performSelectedTabUpdateIfNeeded (TabsContainer.kt:460)
  at com.swmansion.rnscreens.gamma.tabs.container.TabsContainer.performContainerUpdate (TabsContainer.kt:438)
  at com.swmansion.rnscreens.gamma.tabs.container.TabsContainer.flushPendingUpdates (TabsContainer.kt:194)
  at com.swmansion.rnscreens.gamma.tabs.host.TabsHost.didMountItems (TabsHost.kt:197)
  at com.facebook.react.fabric.FabricUIManager$MountItemDispatchListener.didMountItems (FabricUIManager.java:1381)
  at com.facebook.react.fabric.mounting.MountItemDispatcher.dispatchMountItems (MountItemDispatcher.kt:273)
  at com.facebook.react.fabric.mounting.MountItemDispatcher.tryDispatchMountItems (MountItemDispatcher.kt:93)
  at com.facebook.react.fabric.FabricUIManager$2.runGuarded (FabricUIManager.java:930)
  at com.facebook.react.bridge.GuardedRunnable.run (GuardedRunnable.kt:19)
  at com.facebook.react.fabric.FabricUIManager.scheduleMountItem (FabricUIManager.java:933)
  at com.swmansion.reanimated.NativeProxy.performOperations (NativeProxy.kt)
  at com.swmansion.reanimated.NodesManager.performOperations (NodesManager.kt:121)
  at com.swmansion.reanimated.NodesManager.performOperationsRespectingDrawPass$react_native_reanimated_release (NodesManager.kt:137)
  at com.swmansion.reanimated.NodesManager.onEventDispatch (NodesManager.kt:212)
  at com.facebook.react.uimanager.events.FabricEventDispatcher.dispatchEvent (FabricEventDispatcher.kt:46)
  at com.swmansion.rnscreens.gamma.tabs.screen.TabsScreenEventEmitter.emitOnDidAppear (TabsScreenEventEmitter.kt:23)
  at com.swmansion.rnscreens.gamma.tabs.screen.TabsScreenFragment.onResume (TabsScreenFragment.kt:28)
  at androidx.fragment.app.Fragment.performResume (Fragment.java:3210)
  at androidx.fragment.app.FragmentStateManager.resume (FragmentStateManager.java:666)
  at androidx.fragment.app.FragmentStateManager.moveToExpectedState (FragmentStateManager.java:310)
  at androidx.fragment.app.FragmentStore.moveToExpectedState (FragmentStore.java:114)
  at androidx.fragment.app.FragmentManager.moveToState (FragmentManager.java:1685)
  at androidx.fragment.app.FragmentManager.dispatchStateChange (FragmentManager.java:3319)
  at androidx.fragment.app.FragmentManager.dispatchResume (FragmentManager.java:3251)
  at androidx.fragment.app.Fragment.performResume (Fragment.java:3219)
  at androidx.fragment.app.FragmentStateManager.resume (FragmentStateManager.java:666)
  at androidx.fragment.app.FragmentStateManager.moveToExpectedState (FragmentStateManager.java:310)
  at androidx.fragment.app.FragmentStore.moveToExpectedState (FragmentStore.java:114)
  at androidx.fragment.app.FragmentManager.moveToState (FragmentManager.java:1685)
  at androidx.fragment.app.FragmentManager.dispatchStateChange (FragmentManager.java:3319)
  at androidx.fragment.app.FragmentManager.dispatchResume (FragmentManager.java:3251)
  at androidx.fragment.app.FragmentController.dispatchResume (FragmentController.java:285)
  at androidx.fragment.app.FragmentActivity.onResumeFragments (FragmentActivity.java:333)
  at androidx.fragment.app.FragmentActivity.onPostResume (FragmentActivity.java:322)
  at androidx.appcompat.app.AppCompatActivity.onPostResume (AppCompatActivity.java:232)
  at android.app.Activity.performResume (Activity.java:9718)
  at android.app.ActivityThread.performResumeActivity (ActivityThread.java:6239)

Reanimated configuration

This crash involves Reanimated synchronously flushing mount items from within the onDidAppear event dispatch. The relevant versions are react-native-reanimated 4.4.1 and react-native-worklets 0.9.2, with the following static feature flags in our package.json:

"reanimated": {
  "staticFeatureFlags": {
    "ANDROID_SYNCHRONOUSLY_UPDATE_UI_PROPS": true,
    "IOS_SYNCHRONOUSLY_UPDATE_UI_PROPS": true
  }
}

The ANDROID_SYNCHRONOUSLY_UPDATE_UI_PROPS: true flag is likely significant here: it causes NodesManager.onEventDispatch to synchronously performOperations → FabricUIManager.scheduleMountItem, which is what drives the re-entrant mount flush (TabsHost.didMountItems → TabsContainer.updateSelectedFragment → commitNowAllowingStateLoss) while the FragmentManager is still executing the resume transaction. It's possible the crash only reproduces with this flag enabled.

Related issues

The exception class matches #2318 / #1506, but those occur on the legacy ScreenContainer.onUpdate path — this report is on the new Gamma Tabs API (gamma.tabs.container.TabsContainer.updateSelectedFragment) and is triggered re-entrantly from Fragment.onResume. PR #3996 touches the same setSelectedItemIdWithActionOrigin code path.

Steps to reproduce

This was captured in the wild (Google Play Console) on a production release build, so we do not have deterministic local repro steps yet. Based on the stack trace it occurs during activity resume while a Gamma Tabs container has pending updates — likely returning to the app/foregrounding the activity while a tab selection update is in flight. The relevant sequence is Activity.onResume → TabsScreenFragment.onResume → emitOnDidAppear → Reanimated synchronous mount flush → TabsContainer.updateSelectedFragment → commitNowAllowingStateLoss.

1. Use the Gamma Tabs API (bottom tab navigation) with Reanimated.
2. Trigger a tab selection update around the time the activity is resuming/returning to foreground.
3. Crash on resume.

Snack or a link to a repository

No reproduction available — captured via Google Play Console crash reporting on a production release build. (I can provide additional Play Console details if helpful.)

Screens version

4.25.2

React Native version

0.85.3

Platforms

Android

JavaScript runtime

Hermes

Workflow

Expo managed workflow

Architecture

Fabric (New Architecture)

Build type

Release mode

Device

Real device

Device model

Samsung Galaxy S23 (Android 16, SDK 36)

Acknowledgements

Yes

[github-actions]

Hey! 👋

The issue doesn't seem to contain a minimal reproduction.

Could you provide a snack or a link to a GitHub repository under your username that reproduces the problem?

[t0maboro]

Hi @tomekzaw, thanks for reporting this issue and for sharing the detailed information.

I have analyzed the stacktrace to understand this crash flow. The issue stems from a synchronous update in Fabric, which triggers a Fragment transaction while the FragmentManager is already locked during the resume phase.

Here is the step-by-step breakdown of the execution flow:

1. App Resumes

ActivityThread.handleResumeActivity is called. This most likely happens when the app returns from the background (since the TabsScreen Fragment is already in the FragmentStore).

2. Activity Resume Flow

This triggers ActivityThread.performActivity, which calls performResume on the specific Activity:

mInstrumentation.callActivityOnResume(this); // calls activity.onResume() internally
...
mFragments.dispatchResume();
mFragments.execPendingActions();
onPostResume();

At this point, it transitions all Fragments associated with a specific FragmentController to the resumed state.

3. FragmentManager Locks Executing Actions

In onPostResume, the flow goes through AppCompatActivity to FragmentActivity. FragmentActivity calls onResumeFragments, which calls FragmentManager.dispatchStateChange(RESUMED).

Crucially, this is where the lock is acquired:

private void dispatchStateChange(int nextState) {
    try {
        mExecutingActions = true; // <--- LOCK ACQUIRED HERE
        mFragmentStore.dispatchStateChange(nextState);

4. Propagating Resume signal to Fragments

The FragmentStore iterates over all FragmentStateManagers, waking up fragments via mFragment.performResume(). The Fragment then takes its childFragmentManager and propagates the resume state down the tree. This is how we're reaching our TabsScreenFragment.

5. Reanimated Interception

Our TabsScreenFragment emits the onDidAppear event. Reanimated, which has a listener attached to the FabricEventDispatcher, intercepts this event and calls performOperations. This performs a commit to the ShadowTree.

6. Synchronous Mounting (The Catalyst)

This commit triggers FabricUIManager.scheduleMountItem. Following the delegate->xxxDidFinishTransaction path, this results in a synchronous mounting. The execution flows through tryDispatchMountItems -> dispatchMountItems -> didMountItems, eventually reaching our TabsHost.

7. The Crash

At this point, we flush updates. According to the stack trace, the selected tab changes in TabsContainer.onMenuItemSelected.

Because of this update, we call commitNowAllowingStateLoss. However, we are still inside the original call stack that holds the mExecutingActions = true lock.

This hits the safety check in FragmentManager, resulting in the crash:

private void ensureExecReady(boolean allowStateLoss) {
    if (mExecutingActions) {
        throw new IllegalStateException("FragmentManager is already executing transactions"); // <--- CRASH
    }
}

---

Needing help with reproduction

While I fully understand why this is crashing based on the stack trace, I haven't been able to reproduce this on my side.

The selected tab change it always falls into subsequent asynchronous didMountItems call rather than caching the onResume callback happening synchronously while the lock is held.

It would be great if someone running into this issue could help us with preparing a reproduction. A repo with MRE or sharing some ideas how can we trigger the mentioned synchronous update on resume would be helpful for us to investigate it further.