PrefetchOperationCallbackAdapter.onSuccess NPE crash caused by lowered webkit dependency in 11.2.0

[aceofc]

[REQUIRED] Step 1: Describe your environment

• Unity version: 6000.0.75f1
• Google Mobile Ads Unity plugin version: 11.2.0 (regression)
• Last known working version: 11.1.0
• Plugin installation method: UPM
• GMA Android SDK architecture: Next-Gen SDK (enabled)
• Platform: Android
• Scripting backend: IL2CPP, arm64-v8a
• Affected OS / devices (production):
  • Android 13 - Samsung SM-A715F
  • Android 15 - Xiaomi 23073RPBFG
  • Android 16 - Xiaomi 24090RA29G
• Mediation adapters: AppLovin 8.7.3, ironSource 4.5.1, Unity Ads 3.18.0, DT Exchange 3.5.8

[REQUIRED] Step 2: Describe the problem

Regression introduced in 11.2.0. The exact same app - same Next-Gen setting,
same mediation adapters, no changes to our ad code - ran fine on 11.1.0 and
started crashing in production immediately after upgrading to 11.2.0.

The crash is a fatal NPE inside androidx.webkit, in the WebView prefetch
callback path (PrefetchOperationCallbackAdapter$1.onSuccess), dispatched via
the chromium boundary-interface reflection proxy on a System WebView thread.
It happens on cold start, during the ad init/load window.

Suspected root cause: the 11.2.0 changelog adds
next_gen_resolution_strategy.gradle to "use lower webkit and
error_prone_annotation library to support older Unity Editors." This lowers the
androidx.webkit version. The crash is precisely in androidx.webkit's
PrefetchOperationCallbackAdapter.onSuccess, an API that is recent and still
being stabilized upstream. The lowered webkit version pulled in by 11.2.0 appears
to trigger this NPE, which did not occur with the webkit version resolved by 11.1.0.

Deobfuscated stack trace

Exception java.lang.Error:
  at androidx.webkit.internal.PrefetchOperationCallbackAdapter$1.onSuccess (PrefetchOperationCallbackAdapter.java:46)
  at java.lang.reflect.Method.invoke
  at org.chromium.support_lib_boundary.util.BoundaryInterfaceReflectionUtil$InvocationHandlerWithDelegateGetter.invoke (BoundaryInterfaceReflectionUtil.java:203)
  at java.lang.reflect.Proxy.invoke (Proxy.java:1006)
  at $Proxy28.onSuccess (Unknown Source)
  at WV.r22.run (chromium-SystemWebViewGoogle6432.aab-stable-777817803:37)
  at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1167)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:641)
  at java.lang.Thread.run (Thread.java:919)

Steps to reproduce

1. Plugin 11.2.0, Next-Gen GMA Android SDK enabled, mediation configured.
2. Cold start the app; ad initialization / loading begins.
3. Crash on a WebView thread in PrefetchOperationCallbackAdapter.onSuccess.
   Production-only, not deterministically reproducible.

What we'd like

• Restore the androidx.webkit version used by 11.1.0, or
• Make next_gen_resolution_strategy.gradle opt-in / not force a lower webkit for
  projects that don't need older-Editor support, since the lowered version
  introduces this crash.

Notes

• Possibly related but distinct from [ANR] Main thread deadlocked in art::ConditionVariable::WaitHoldingLocks via com.google.android.gms.ads.internal.webview.ai.onDraw #4140 (that one is an ANR on the main thread
  in ...webview.ai.onDraw on the standard SDK; ours is a fatal NPE on a WebView
  worker thread in androidx.webkit prefetch on Next-Gen).

[yacynth]

This beging suddently this 2026/06/03

Workaround for androidx.webkit prefetch crash in GMA SDK WebView URL prefetch flow.

The issue seems related to R8 shrinking/obfuscation of androidx.webkit /

Chromium support-lib boundary classes that are accessed reflectively.

-keep class androidx.webkit.** { ; }
-keep class org.chromium.support_lib_boundary.* { *; }

[vARDAmirr]

This beging suddently this 2026/06/03

Workaround for androidx.webkit prefetch crash in GMA SDK WebView URL prefetch flow.

The issue seems related to R8 shrinking/obfuscation of androidx.webkit /

Chromium support-lib boundary classes that are accessed reflectively.

-keep class androidx.webkit.** { ; } -keep class org.chromium.support_lib_boundary.* { *; }

Thanks, adding the following Proguard rules fixed the issue for me:

-keep class androidx.webkit.** { *; }
-keep class org.chromium.support_lib_boundary.** { *; }

[solssi]

This beging suddently this 2026/06/03

Workaround for androidx.webkit prefetch crash in GMA SDK WebView URL prefetch flow.

The issue seems related to R8 shrinking/obfuscation of androidx.webkit /

Chromium support-lib boundary classes that are accessed reflectively.

-keep class androidx.webkit.** { ; } -keep class org.chromium.support_lib_boundary.* { *; }

Thanks, adding the following Proguard rules fixed the issue for me:

-keep class androidx.webkit.** { *; }
-keep class org.chromium.support_lib_boundary.** { *; }

It doesn't work, I've tried but issue is still happening. Thanks for sharing though

[aceofc]

This beging suddently this 2026/06/03

Workaround for androidx.webkit prefetch crash in GMA SDK WebView URL prefetch flow.

The issue seems related to R8 shrinking/obfuscation of androidx.webkit /

Chromium support-lib boundary classes that are accessed reflectively.

-keep class androidx.webkit.** { ; } -keep class org.chromium.support_lib_boundary.* { *; }

Adding those lines fixed the issue, thanks