[Bug] Crash when switching tabs in ViewPager2 due to LayoutTransition conflict

[JeffHuang04]

Describe the bug

The app crashes when switching tabs (ViewPager2 pages) in the browser.

The crash is caused by a ViewGroup using LayoutTransition (or animateLayoutChanges="true"), which conflicts with ViewPager2's internal scrolling animation and results in an IllegalStateException.

This issue occurs during normal UI interaction and is not specific to test frameworks.

How to Reproduce

Steps to reproduce the behavior:

1. Launch the DuckDuckGo app
2. Open multiple tabs in the browser
3. Trigger a tab switch (e.g., via tab manager or programmatic navigation)
4. Observe crash

I found this crash by automated testing tool.

Logcat shows:

--------- beginning of crash
03-30 01:21:50.933 20810 20810 E AndroidRuntime: FATAL EXCEPTION: main
03-30 01:21:50.933 20810 20810 E AndroidRuntime: Process: com.duckduckgo.mobile.android.debug, PID: 20810
03-30 01:21:50.933 20810 20810 E AndroidRuntime: java.lang.IllegalStateException: Page(s) contain a ViewGroup with a LayoutTransition (or animateLayoutChanges="true"), which interferes with the scrolling animation. Make sure to call getLayoutTransition().setAnimateParentHierarchy(false) on all ViewGroups with a LayoutTransition before an animation is started.
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at androidx.viewpager2.widget.ScrollEventAdapter.updateScrollEventValues(ScrollEventAdapter.java:271)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at androidx.viewpager2.widget.ScrollEventAdapter.getRelativeScrollPosition(ScrollEventAdapter.java:406)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at androidx.viewpager2.widget.ViewPager2.setCurrentItemInternal(ViewPager2.java:654)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at androidx.viewpager2.widget.ViewPager2.setCurrentItem(ViewPager2.java:614)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at com.duckduckgo.app.browser.BrowserActivity.onMoveToTabRequested$lambda$51(BrowserActivity.kt:1470)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at com.duckduckgo.app.browser.BrowserActivity.$r8$lambda$JCC60xI_JcBNHNTavCcUC05kgBA(Unknown Source:0)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at com.duckduckgo.app.browser.BrowserActivity$$ExternalSyntheticLambda5.run(D8$$SyntheticClass:0)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:873)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:99)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at android.os.Looper.loop(Looper.java:193)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6669)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
03-30 01:21:50.933 20810 20810 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
03-30 01:21:51.908 2603 18416 E ActivityThread: Failed to find provider info for com.google.android.apps.gsa.testing.ui.audio.recorded

the action sequence before the crash

action: 9@back
action: 3@click resource-id=com.duckduckgo.mobile.android.debug:id/aiChatIconMenu :android.widget.ImageView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 10@scroll direction=down
action: 3@click className=android.widget.TextView,instance=0 :android.widget.TextView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 2@edit resource-id=com.duckduckgo.mobile.android.debug:id/omnibarTextInput :android.widget.EditText@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 1@click resource-id=com.duckduckgo.mobile.android.debug:id/backIcon :android.widget.ImageView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 3@click className=android.widget.TextView,instance=0 :android.widget.TextView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 9@click className=android.widget.Button,instance=0 :android.widget.Button@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 3@click className=android.widget.TextView,instance=0 :android.widget.TextView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 4@click className=android.widget.TextView,instance=0 :android.widget.TextView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 2@click resource-id=com.duckduckgo.mobile.android.debug:id/duckAIToolbarButton :android.widget.Button@
action: 11@scroll direction=up
action: 4@click resource-id=com.duckduckgo.mobile.android.debug:id/fireIconImageView :android.widget.ImageView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 5@back
action: 3@click className=android.widget.TextView,instance=0 :android.widget.TextView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 5@clickLong className=android.widget.TextView,instance=0 :android.widget.TextView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 16@edit resource-id=com.duckduckgo.mobile.android.debug:id/omnibarTextInput :android.widget.EditText@weather forecast today
action: 1@click resource-id=com.duckduckgo.mobile.android.debug:id/fireIconImageView :android.widget.ImageView@recycler items_com.duckduckgo.app.browser.BrowserActivity_000000000
action: 1@click resource-id=com.duckduckgo.mobile.android.debug:id/leadingIcon :android.widget.ImageView@

Expected behavior

Switching tabs should work smoothly without crashing, regardless of layout animations inside child views.

Environment

- DDG App Version:5.274.0 (debug intern build)
- Device:Android Emulator (medium phone)
- OS: Android 9

[github-actions]

Thank you for opening an Issue in our Repository.
The issue has been forwarded to the team and we'll follow up as soon as we have time to investigate.
As stated in our Contribution Guidelines, requests for feedback should be addressed via the Feedback section in the Android app.

[catalinradoiu]

@JeffHuang04 thanks for reporting this. I tried to follow the steps provided, though I haven't been able to reproduce it on my side just yet. We'll look into it as we prioritise our work. In the meantime, if you come across any extra details on how to reproduce it more reliably, feel free to share them here.

[JeffHuang04]

Hello，my inference may serve as a useful reference.
Due to the use of automated testing tools, the system often undergoes forced restarts.
This is my inference.
Trigger chain: Back button press (KEYCODE_BACK) → Force-stop of DuckDuckGo app → Immediate monkey test launch on same package without proper cleanup or activity lifecycle reset

Root cause: The app attempted to access a UI component (likely a Fragment or ViewModel) after the activity was destroyed due to force-stop, violating Android's lifecycle contract. The truncated stack trace suggests an IllegalStateException from androidx.lifecycle or androidx.fragment — commonly thrown when observing a LiveData or accessing a ViewModel after its owner is detached/destroyed.