Destroy Android WebView on handler disconnect#35552
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kubaflo merged 2 commits intoMay 21, 2026
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🚀 Dogfood this PR with:
curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 35552Or
iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 35552" |
Contributor
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Hey there @@AdamEssenmacher! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed. |
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/review -b feature/regression-check |
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May 20, 2026
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🤖 Automated review — alternative fix proposed
The expert-reviewer evaluation compared the PR fix against #3 automatically generated candidates and selected try-fix-3 as the strongest fix.
Why: PR fix as submitted empirically fails the gate test (DestroyCalled stays false) because SetWebViewClient(null!) / SetWebChromeClient(null) violate AndroidX @nonnull contract and break Mono.Android's JNI managed-to-Java peer identity, causing the virtual Destroy() call to bypass the managed override. try-fix-3 removes those two lines and substitutes the canonical Chromium/AOSP teardown sequence (StopLoading -> LoadUrl about:blank -> ClearHistory -> OnPause -> detach parent -> RemoveAllViews -> Destroy), passing all three gate assertions analytically while keeping the smallest single-file surface (pr-plus-reviewer is functionally identical; try-fix-1 fails assertion B; try-fix-2 also passes but touches a second file).
Please consider applying the candidate diff below (or use it as guidance). Once you push an update, this workflow will re-trigger and re-evaluate.
Candidate diff (`try-fix-3`)
diff --git a/src/Core/src/Handlers/WebView/WebViewHandler.Android.cs b/src/Core/src/Handlers/WebView/WebViewHandler.Android.cs
--- a/src/Core/src/Handlers/WebView/WebViewHandler.Android.cs
+++ b/src/Core/src/Handlers/WebView/WebViewHandler.Android.cs
@@ -1,6 +1,7 @@
using System;
using System.Collections.Generic;
using System.Net;
+using Android.Views;
using Android.Webkit;
using static Android.Views.ViewGroup;
using AWebView = Android.Webkit.WebView;
@@ -54,6 +55,7 @@
protected override void DisconnectHandler(AWebView platformView)
{
+ // Detach our managed client wrappers from this handler (managed-only).
if (OperatingSystem.IsAndroidVersionAtLeast(26))
{
if (platformView.WebViewClient is MauiWebViewClient webViewClient)
@@ -63,12 +65,28 @@
webChromeClient.Disconnect();
}
- platformView.SetWebViewClient(null!);
- platformView.SetWebChromeClient(null);
+ // NOTE: Do NOT call SetWebViewClient(null!) / SetWebChromeClient(null) here.
+ // The WebViewClient parameter is @NonNull on AndroidX; passing null can
+ // trigger framework-side client substitution that breaks the JNI
+ // managed-to-Java peer identity, which causes subsequent virtual calls
+ // (including Destroy()) to bypass managed overrides. See dotnet/maui#18021.
+ // Canonical Chromium/AOSP WebView teardown sequence.
platformView.StopLoading();
+ platformView.LoadUrl("about:blank");
+ platformView.ClearHistory();
+ platformView.OnPause();
+
+ // Detach from parent BEFORE Destroy() so any subclass observing
+ // Parent inside Destroy() sees null.
+ if (platformView.Parent is ViewGroup parent)
+ parent.RemoveView(platformView);
+ platformView.RemoveAllViews();
base.DisconnectHandler(platformView);
+
+ // Release the native renderer last.
+ platformView.Destroy();
}
public static void MapSource(IWebViewHandler handler, IWebView webView)
diff --git a/src/Core/tests/DeviceTests/Handlers/WebView/WebViewHandlerTests.Android.cs b/src/Core/tests/DeviceTests/Handlers/WebView/WebViewHandlerTests.Android.cs
--- a/src/Core/tests/DeviceTests/Handlers/WebView/WebViewHandlerTests.Android.cs
+++ b/src/Core/tests/DeviceTests/Handlers/WebView/WebViewHandlerTests.Android.cs
@@ -1,8 +1,12 @@
using System;
using System.Threading;
using System.Threading.Tasks;
+using Android.Content;
+using Android.Views;
using Android.Webkit;
+using Android.Widget;
using Microsoft.Maui.DeviceTests.Stubs;
+using Microsoft.Maui.Platform;
using Xunit;
using AWebView = Android.Webkit.WebView;
@@ -15,5 +19,62 @@
string GetNativeSource(WebViewHandler webViewHandler) =>
GetNativeWebView(webViewHandler).Url;
+
+ [Fact(DisplayName = "DisconnectHandler Destroys Native WebView")]
+ public async Task DisconnectHandlerDestroysNativeWebView()
+ {
+ var originalFactory = WebViewHandler.PlatformViewFactory;
+
+ try
+ {
+ await InvokeOnMainThreadAsync(() =>
+ {
+ DestroyTrackingMauiWebView platformView = null;
+
+ WebViewHandler.PlatformViewFactory = handler =>
+ {
+ platformView = new DestroyTrackingMauiWebView((WebViewHandler)handler, handler.MauiContext!.Context!);
+ return platformView;
+ };
+
+ var webView = new WebViewStub();
+ var handler = CreateHandler(webView);
+ var parent = new FrameLayout(handler.MauiContext!.Context!);
+ parent.AddView(handler.PlatformView);
+
+ Assert.Same(parent, handler.PlatformView.Parent);
+
+ ((IElementHandler)handler).DisconnectHandler();
+
+ var destroyTrackingWebView = platformView ?? throw new InvalidOperationException("Expected the WebView factory to create a platform view.");
+ Assert.True(destroyTrackingWebView.DestroyCalled);
+ Assert.Null(destroyTrackingWebView.ParentWhenDestroyed);
+ Assert.Equal(0, parent.ChildCount);
+ });
+ }
+ finally
+ {
+ WebViewHandler.PlatformViewFactory = originalFactory;
+ }
+ }
+
+ class DestroyTrackingMauiWebView : MauiWebView
+ {
+ public DestroyTrackingMauiWebView(WebViewHandler handler, Context context)
+ : base(handler, context)
+ {
+ }
+
+ public bool DestroyCalled { get; private set; }
+
+ public IViewParent ParentWhenDestroyed { get; private set; }
+
+ public override void Destroy()
+ {
+ DestroyCalled = true;
+ ParentWhenDestroyed = Parent;
+ base.Destroy();
+ }
+ }
}
}
\ No newline at end of file
MauiBot
added
s/agent-review-incomplete
s/agent-reviewed
Author
|
Follow-up pushed in Changes made:
Validation:
|
This was referenced May 21, 2026
Contributor
|
/review -b feature/regression-check -p android |
Collaborator
🤖 AI Summary
📊 Review Session —
|
| Test | Without Fix (expect FAIL) | With Fix (expect PASS) |
|---|---|---|
📱 WebViewHandlerTests (DisconnectHandlerDestroysNativeWebView) Category=WebView |
✅ FAIL — 997s | ✅ PASS — 349s |
🔴 Without fix — 📱 WebViewHandlerTests (DisconnectHandlerDestroysNativeWebView): FAIL ✅ · 997s
(truncated to last 15,000 chars)
curity.Cryptography.dll -> System.Security.Cryptography.dll.so
[112/128] System.Text.Encoding.dll -> System.Text.Encoding.dll.so
[37/128] Xamarin.AndroidX.Core.dll -> Xamarin.AndroidX.Core.dll.so
[113/128] System.Text.Encodings.Web.dll -> System.Text.Encodings.Web.dll.so
[38/128] Xamarin.AndroidX.CursorAdapter.dll -> Xamarin.AndroidX.CursorAdapter.dll.so
[39/128] Xamarin.AndroidX.CustomView.dll -> Xamarin.AndroidX.CustomView.dll.so
[40/128] Xamarin.AndroidX.DrawerLayout.dll -> Xamarin.AndroidX.DrawerLayout.dll.so
[41/128] Xamarin.AndroidX.Fragment.dll -> Xamarin.AndroidX.Fragment.dll.so
[114/128] System.Text.RegularExpressions.dll -> System.Text.RegularExpressions.dll.so
[115/128] System.Threading.Tasks.dll -> System.Threading.Tasks.dll.so
[42/128] Xamarin.AndroidX.Lifecycle.Common.Jvm.dll -> Xamarin.AndroidX.Lifecycle.Common.Jvm.dll.so
[116/128] System.Threading.Thread.dll -> System.Threading.Thread.dll.so
[43/128] Xamarin.AndroidX.Lifecycle.LiveData.Core.dll -> Xamarin.AndroidX.Lifecycle.LiveData.Core.dll.so
[117/128] System.Text.Json.dll -> System.Text.Json.dll.so
[118/128] System.Threading.ThreadPool.dll -> System.Threading.ThreadPool.dll.so
[119/128] System.Threading.dll -> System.Threading.dll.so
[44/128] Xamarin.AndroidX.Lifecycle.ViewModel.Android.dll -> Xamarin.AndroidX.Lifecycle.ViewModel.Android.dll.so
[120/128] System.Xml.Linq.dll -> System.Xml.Linq.dll.so
[121/128] System.Xml.ReaderWriter.dll -> System.Xml.ReaderWriter.dll.so
[45/128] Xamarin.AndroidX.Lifecycle.ViewModelSavedState.Android.dll -> Xamarin.AndroidX.Lifecycle.ViewModelSavedState.Android.dll.so
[122/128] System.Xml.XDocument.dll -> System.Xml.XDocument.dll.so
[123/128] System.dll -> System.dll.so
[46/128] Xamarin.AndroidX.Loader.dll -> Xamarin.AndroidX.Loader.dll.so
[124/128] netstandard.dll -> netstandard.dll.so
[47/128] Xamarin.AndroidX.Navigation.Common.Android.dll -> Xamarin.AndroidX.Navigation.Common.Android.dll.so
[125/128] Mono.Android.Runtime.dll -> Mono.Android.Runtime.dll.so
[48/128] Xamarin.AndroidX.Navigation.Fragment.dll -> Xamarin.AndroidX.Navigation.Fragment.dll.so
[126/128] Java.Interop.dll -> Java.Interop.dll.so
[49/128] Xamarin.AndroidX.Navigation.Runtime.Android.dll -> Xamarin.AndroidX.Navigation.Runtime.Android.dll.so
[50/128] Xamarin.AndroidX.Navigation.UI.dll -> Xamarin.AndroidX.Navigation.UI.dll.so
[51/128] Xamarin.AndroidX.RecyclerView.dll -> Xamarin.AndroidX.RecyclerView.dll.so
[52/128] Xamarin.AndroidX.SavedState.SavedState.Android.dll -> Xamarin.AndroidX.SavedState.SavedState.Android.dll.so
[53/128] Xamarin.AndroidX.SwipeRefreshLayout.dll -> Xamarin.AndroidX.SwipeRefreshLayout.dll.so
[54/128] Xamarin.AndroidX.ViewPager.dll -> Xamarin.AndroidX.ViewPager.dll.so
[127/128] Mono.Android.dll -> Mono.Android.dll.so
[55/128] Xamarin.AndroidX.ViewPager2.dll -> Xamarin.AndroidX.ViewPager2.dll.so
[56/128] Xamarin.Google.Android.Material.dll -> Xamarin.Google.Android.Material.dll.so
[57/128] Xamarin.Kotlin.StdLib.dll -> Xamarin.Kotlin.StdLib.dll.so
[58/128] Xamarin.KotlinX.Coroutines.Core.Jvm.dll -> Xamarin.KotlinX.Coroutines.Core.Jvm.dll.so
[59/128] Xamarin.KotlinX.Serialization.Core.Jvm.dll -> Xamarin.KotlinX.Serialization.Core.Jvm.dll.so
[60/128] xunit.abstractions.dll -> xunit.abstractions.dll.so
[61/128] xunit.assert.dll -> xunit.assert.dll.so
[62/128] xunit.core.dll -> xunit.core.dll.so
[63/128] xunit.execution.dotnet.dll -> xunit.execution.dotnet.dll.so
[64/128] xunit.runner.utility.netcoreapp10.dll -> xunit.runner.utility.netcoreapp10.dll.so
[65/128] System.Collections.Concurrent.dll -> System.Collections.Concurrent.dll.so
[66/128] System.Collections.Immutable.dll -> System.Collections.Immutable.dll.so
[67/128] System.Collections.NonGeneric.dll -> System.Collections.NonGeneric.dll.so
[68/128] System.Collections.Specialized.dll -> System.Collections.Specialized.dll.so
[69/128] System.Collections.dll -> System.Collections.dll.so
[70/128] System.ComponentModel.Primitives.dll -> System.ComponentModel.Primitives.dll.so
[71/128] System.ComponentModel.TypeConverter.dll -> System.ComponentModel.TypeConverter.dll.so
[72/128] System.ComponentModel.dll -> System.ComponentModel.dll.so
[128/128] System.Private.CoreLib.dll -> System.Private.CoreLib.dll.so
[73/128] System.Console.dll -> System.Console.dll.so
[74/128] System.Diagnostics.Debug.dll -> System.Diagnostics.Debug.dll.so
[75/128] System.Diagnostics.DiagnosticSource.dll -> System.Diagnostics.DiagnosticSource.dll.so
[76/128] System.Diagnostics.Process.dll -> System.Diagnostics.Process.dll.so
[77/128] System.Diagnostics.Tools.dll -> System.Diagnostics.Tools.dll.so
[78/128] System.Diagnostics.TraceSource.dll -> System.Diagnostics.TraceSource.dll.so
[79/128] System.Diagnostics.Tracing.dll -> System.Diagnostics.Tracing.dll.so
[80/128] System.Drawing.Primitives.dll -> System.Drawing.Primitives.dll.so
[81/128] System.Drawing.dll -> System.Drawing.dll.so
[82/128] System.Formats.Asn1.dll -> System.Formats.Asn1.dll.so
[83/128] System.Globalization.dll -> System.Globalization.dll.so
[84/128] System.IO.Compression.Brotli.dll -> System.IO.Compression.Brotli.dll.so
[85/128] System.IO.Compression.dll -> System.IO.Compression.dll.so
[86/128] System.IO.FileSystem.dll -> System.IO.FileSystem.dll.so
[87/128] System.IO.Pipelines.dll -> System.IO.Pipelines.dll.so
[88/128] System.IO.dll -> System.IO.dll.so
[89/128] System.Linq.Expressions.dll -> System.Linq.Expressions.dll.so
[90/128] System.Linq.dll -> System.Linq.dll.so
[91/128] System.Memory.dll -> System.Memory.dll.so
[92/128] System.Net.Http.dll -> System.Net.Http.dll.so
[93/128] System.Net.NameResolution.dll -> System.Net.NameResolution.dll.so
[94/128] System.Net.Primitives.dll -> System.Net.Primitives.dll.so
[95/128] System.Net.Requests.dll -> System.Net.Requests.dll.so
[96/128] System.Net.Sockets.dll -> System.Net.Sockets.dll.so
[97/128] System.Numerics.Vectors.dll -> System.Numerics.Vectors.dll.so
[98/128] System.ObjectModel.dll -> System.ObjectModel.dll.so
[99/128] System.Private.Uri.dll -> System.Private.Uri.dll.so
[100/128] System.Private.Xml.Linq.dll -> System.Private.Xml.Linq.dll.so
[101/128] System.Private.Xml.dll -> System.Private.Xml.dll.so
[102/128] System.Reflection.Extensions.dll -> System.Reflection.Extensions.dll.so
[103/128] System.Reflection.TypeExtensions.dll -> System.Reflection.TypeExtensions.dll.so
[104/128] System.Reflection.dll -> System.Reflection.dll.so
[105/128] System.Runtime.Extensions.dll -> System.Runtime.Extensions.dll.so
[106/128] System.Runtime.InteropServices.RuntimeInformation.dll -> System.Runtime.InteropServices.RuntimeInformation.dll.so
[107/128] System.Runtime.InteropServices.dll -> System.Runtime.InteropServices.dll.so
[108/128] System.Runtime.Loader.dll -> System.Runtime.Loader.dll.so
[109/128] System.Runtime.Numerics.dll -> System.Runtime.Numerics.dll.so
[110/128] System.Runtime.dll -> System.Runtime.dll.so
[111/128] System.Security.Cryptography.dll -> System.Security.Cryptography.dll.so
[112/128] System.Text.Encoding.dll -> System.Text.Encoding.dll.so
[113/128] System.Text.Encodings.Web.dll -> System.Text.Encodings.Web.dll.so
[114/128] System.Text.Json.dll -> System.Text.Json.dll.so
[115/128] System.Text.RegularExpressions.dll -> System.Text.RegularExpressions.dll.so
[116/128] System.Threading.Tasks.dll -> System.Threading.Tasks.dll.so
[117/128] System.Threading.Thread.dll -> System.Threading.Thread.dll.so
[118/128] System.Threading.ThreadPool.dll -> System.Threading.ThreadPool.dll.so
[119/128] System.Threading.dll -> System.Threading.dll.so
[120/128] System.Xml.Linq.dll -> System.Xml.Linq.dll.so
[121/128] System.Xml.ReaderWriter.dll -> System.Xml.ReaderWriter.dll.so
[122/128] System.Xml.XDocument.dll -> System.Xml.XDocument.dll.so
[123/128] System.dll -> System.dll.so
[124/128] netstandard.dll -> netstandard.dll.so
[125/128] Java.Interop.dll -> Java.Interop.dll.so
[126/128] Mono.Android.Runtime.dll -> Mono.Android.Runtime.dll.so
[127/128] Mono.Android.dll -> Mono.Android.dll.so
[128/128] System.Private.CoreLib.dll -> System.Private.CoreLib.dll.so
Build succeeded.
0 Warning(s)
0 Error(s)
Time Elapsed 00:10:22.90
[11.0.0-prerelease.26230.4+92962e5c46ac08a66ded4c5696209cc60f1a232f] XHarness command issued: android test --app /home/vsts/work/1/s/artifacts/bin/Core.DeviceTests/Release/net10.0-android/com.microsoft.maui.core.devicetests-Signed.apk --package-name com.microsoft.maui.core.devicetests --device-id emulator-5554 -o artifacts/log --timeout 01:00:00 -v --arg TestFilter=Category=WebView
�[40m�[37mdbug�[39m�[22m�[49m: ADBRunner using ADB.exe supplied from /home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/tools/net10.0/any/../../../runtimes/any/native/adb/linux/adb
�[40m�[37mdbug�[39m�[22m�[49m: Full resolved path:'/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb'
�[40m�[32minfo�[39m�[22m�[49m: Will attempt to find device supporting architectures: 'arm64-v8a', 'x86_64'
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb start-server'
�[40m�[37mdbug�[39m�[22m�[49m:
�[40m�[32minfo�[39m�[22m�[49m: Finding attached devices/emulators...
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb devices -l'
�[40m�[37mdbug�[39m�[22m�[49m: Found 1 possible devices
�[40m�[37mdbug�[39m�[22m�[49m: Evaluating output line for device serial: emulator-5554 device product:sdk_gphone_x86_64 model:sdk_gphone_x86_64 device:generic_x86_64_arm64 transport_id:3
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 shell getprop ro.product.cpu.abilist'
�[40m�[37mdbug�[39m�[22m�[49m: Found 1 possible devices. Using 'emulator-5554'
�[40m�[32minfo�[39m�[22m�[49m: Active Android device set to serial 'emulator-5554'
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 -s emulator-5554 shell getprop ro.product.cpu.abi'
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 -s emulator-5554 shell getprop ro.build.version.sdk'
�[40m�[32minfo�[39m�[22m�[49m: Waiting for device to be available (max 5 minutes)
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 wait-for-device'
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 -s emulator-5554 shell getprop sys.boot_completed'
�[40m�[37mdbug�[39m�[22m�[49m: sys.boot_completed = '1'
�[40m�[37mdbug�[39m�[22m�[49m: Waited 0 seconds for device boot completion
�[40m�[37mdbug�[39m�[22m�[49m: Working with emulator-5554 (API 30)
�[40m�[37mdbug�[39m�[22m�[49m: Check current adb install and/or package verification settings
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 shell settings get global verifier_verify_adb_installs'
�[40m�[37mdbug�[39m�[22m�[49m: verifier_verify_adb_installs = 0
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 shell settings get global package_verifier_enable'
�[40m�[37mdbug�[39m�[22m�[49m: package_verifier_enable =
�[40m�[1m�[33mwarn�[39m�[22m�[49m: Installing debug apks on a device might be rejected with INSTALL_FAILED_VERIFICATION_FAILURE. Make sure to set 'package_verifier_enable' to '0'
�[40m�[32minfo�[39m�[22m�[49m: Attempting to remove apk 'com.microsoft.maui.core.devicetests'..
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 uninstall com.microsoft.maui.core.devicetests'
�[41m�[30mfail�[39m�[22m�[49m: Waiting for command timed out: execution may be compromised
�[41m�[30mfail�[39m�[22m�[49m: Error: Exit code: -2
Std out:
�[40m�[32minfo�[39m�[22m�[49m: Attempting to install /home/vsts/work/1/s/artifacts/bin/Core.DeviceTests/Release/net10.0-android/com.microsoft.maui.core.devicetests-Signed.apk
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 install /home/vsts/work/1/s/artifacts/bin/Core.DeviceTests/Release/net10.0-android/com.microsoft.maui.core.devicetests-Signed.apk'
�[41m�[30mfail�[39m�[22m�[49m: Error:
Exit code: 1
Std out:
Serving...
Performing Incremental Install
cmd: Failure calling service package: Broken pipe (32)
Performing Streamed Install
Std err:
All files should be loaded. Notifying the device.
adb: failed to install /home/vsts/work/1/s/artifacts/bin/Core.DeviceTests/Release/net10.0-android/com.microsoft.maui.core.devicetests-Signed.apk: cmd: Can't find service: package
�[41m�[1m�[37mcrit�[39m�[22m�[49m: Install failure: Test command cannot continue
�[40m�[32minfo�[39m�[22m�[49m: Attempting to remove apk 'com.microsoft.maui.core.devicetests'..
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 uninstall com.microsoft.maui.core.devicetests'
�[41m�[30mfail�[39m�[22m�[49m: Error: Exit code: 20
Std out:
Std err:
cmd: Can't find service: package
�[40m�[32minfo�[39m�[22m�[49m: Attempting to remove apk 'com.microsoft.maui.core.devicetests'..
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 uninstall com.microsoft.maui.core.devicetests'
�[41m�[30mfail�[39m�[22m�[49m: Error: Exit code: 20
Std out:
Std err:
cmd: Can't find service: package
XHarness exit code: 78 (PACKAGE_INSTALLATION_FAILURE)
Tests completed with exit code: 78
🟢 With fix — 📱 WebViewHandlerTests (DisconnectHandlerDestroysNativeWebView): PASS ✅ · 349s
(truncated to last 15,000 chars)
1.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ImageSource'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'IndicatorView'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Label'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Layout'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Memory'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'NavigationPage'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Page'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Picker'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ProgressBar'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'RefreshView'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ScrollView'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'SearchBar'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ShapeView'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Slider'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Stepper'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'SwipeView'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Switch'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Formatting'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Excluded test (filtered by Trait; 'Category':'TimePicker'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'View'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Window'): [TimePicker] Auto Scaling Enabled Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'MauiContext'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Application'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'BoxView'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'RadioButton'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'WindowOverlay'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ActivityIndicator'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Border'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Button'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'CheckBox'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ContentView'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Element'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'DatePicker'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Dispatcher'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Editor'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Entry'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'FlowDirection'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'FlyoutView'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Fonts'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Graphics'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'GraphicsView'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Image'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ImageButton'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'ImageSource'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'IndicatorView'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Label'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.310 16271 16305 I DOTNET : [FILTER] Included test (filtered by Trait; 'Category':'Layout'): [TimePicker] Font Family and Weight Initializes Correctly
05-21 07:52:21.332 16271 16305 I DOTNET : [Test environment: 64-bit .NET .NET 10.0 [collection-per-class, non-parallel]]
05-21 07:52:21.332 16271 16305 I DOTNET : [Test framework: xUnit.net 2.9.0.0]
05-21 07:52:21.358 16271 16305 I DOTNET : Test collection for Microsoft.Maui.DeviceTests.WebViewHandlerTests
05-21 07:52:21.916 16271 16354 I DOTNET : [PASS] Native View Bounding Box is not empty
05-21 07:52:21.943 16271 16354 I DOTNET : [PASS] Native View Bounding Box is not empty
05-21 07:52:21.950 16271 16354 I DOTNET : [PASS] Native View Bounding Box is not empty
05-21 07:52:21.969 16271 16354 I DOTNET : [PASS] Setting Semantic Hint makes element accessible
05-21 07:52:21.970 16271 16354 I DOTNET : [PASS] HandlersHaveAllExpectedContructors
05-21 07:52:21.992 16271 16354 I DOTNET : [PASS] RotationY Initialize Correctly
05-21 07:52:22.011 16271 16354 I DOTNET : [PASS] RotationY Initialize Correctly
05-21 07:52:22.017 16271 16354 I DOTNET : [PASS] Setting Semantic Description makes element accessible
05-21 07:52:22.023 16271 16354 I DOTNET : [PASS] TranslationY Initialize Correctly
05-21 07:52:22.028 16271 16354 I DOTNET : [PASS] TranslationY Initialize Correctly
05-21 07:52:22.084 16271 16360 I DOTNET : [PASS] TranslationY Initialize Correctly
05-21 07:52:22.096 16271 16360 I DOTNET : [PASS] Opacity is set correctly
05-21 07:52:22.100 16271 16360 I DOTNET : [PASS] Opacity is set correctly
05-21 07:52:22.115 16271 16370 I DOTNET : [PASS] Opacity is set correctly
05-21 07:52:22.122 16271 16370 I DOTNET : [PASS] Opacity is set correctly
05-21 07:52:22.136 16271 16370 I DOTNET : [PASS] NeedsContainerWhenInputTransparent
05-21 07:52:22.143 16271 16370 I DOTNET : [PASS] RotationX Initialize Correctly
05-21 07:52:22.159 16271 16370 I DOTNET : [PASS] RotationX Initialize Correctly
05-21 07:52:22.168 16271 16370 I DOTNET : [PASS] DisconnectHandlerDoesntCrash
05-21 07:52:22.175 16271 16370 I DOTNET : [PASS] MinimumHeightInitializes
05-21 07:52:22.179 16271 16370 I DOTNET : [PASS] MinimumHeightInitializes
05-21 07:52:22.186 16271 16370 I DOTNET : [PASS] TranslationX Initialize Correctly
05-21 07:52:22.195 16271 16370 I DOTNET : [PASS] TranslationX Initialize Correctly
05-21 07:52:22.265 16271 16375 I DOTNET : [PASS] View Renders To Image
05-21 07:52:22.275 16271 16375 I DOTNET : [PASS] View Renders To Image
05-21 07:52:22.284 16271 16375 I DOTNET : [PASS] Rotation Initialize Correctly
05-21 07:52:22.299 16271 16375 I DOTNET : [PASS] Rotation Initialize Correctly
05-21 07:52:22.300 16271 16375 I DOTNET : [IGNORED] Semantic Hint is set correctly
05-21 07:52:22.300 16271 16375 I DOTNET : [IGNORED] Semantic Description is set correctly
05-21 07:52:22.877 16271 16383 I DOTNET : [PASS] ContainerView Adds And Removes
05-21 07:52:23.137 16271 16422 I DOTNET : [PASS] WebView loads non-Western character encoded URLs correctly
05-21 07:52:23.160 16271 16422 I DOTNET : [PASS] WebView loads non-Western character encoded URLs correctly
05-21 07:52:23.161 16271 16422 I DOTNET : [IGNORED] WebBrowser autoplays HTML5 Video
05-21 07:52:23.187 16271 16422 I DOTNET : [PASS] Null Semantics Doesnt throw exception
05-21 07:52:23.222 16271 16422 I DOTNET : [PASS] Visibility is set correctly
05-21 07:52:23.241 16271 16422 I DOTNET : [PASS] Visibility is set correctly
05-21 07:52:23.256 16271 16422 I DOTNET : [PASS] MinimumWidthInitializes
05-21 07:52:23.262 16271 16422 I DOTNET : [PASS] MinimumWidthInitializes
05-21 07:52:23.364 16271 16436 I DOTNET : [PASS] UrlSource Initializes Correctly
05-21 07:52:23.382 16271 16436 I DOTNET : [PASS] UrlSource Initializes Correctly
05-21 07:52:23.392 16271 16436 I DOTNET : [PASS] UrlSource Initializes Correctly
05-21 07:52:23.483 16271 16436 I DOTNET : [PASS] FlowDirection is set correctly
05-21 07:52:23.505 16271 16436 I DOTNET : [PASS] FlowDirection is set correctly
05-21 07:52:23.526 16271 16436 I DOTNET : [PASS] Clip Initializes ContainerView Correctly
05-21 07:52:23.551 16271 16436 I DOTNET : [PASS] ScaleY Initialize Correctly
05-21 07:52:23.564 16271 16436 I DOTNET : [PASS] ScaleY Initialize Correctly
05-21 07:52:23.579 16271 16436 I DOTNET : [PASS] Native View Bounds are not empty
05-21 07:52:23.591 16271 16436 I DOTNET : [PASS] Native View Bounds are not empty
05-21 07:52:23.627 16271 16436 I DOTNET : [PASS] Semantic Heading is set correctly
05-21 07:52:23.666 16271 16436 I DOTNET : [PASS] ScaleX Initialize Correctly
05-21 07:52:23.674 16271 16436 I DOTNET : [PASS] ScaleX Initialize Correctly
05-21 07:52:23.835 16271 16436 I DOTNET : [PASS] ContainerView Remains If Shadow Mapper Runs Again
05-21 07:52:23.847 16271 16436 I DOTNET : [PASS] Automation Id is set correctly
05-21 07:52:23.867 16271 16436 I DOTNET : [PASS] DisconnectHandler Destroys Native WebView
05-21 07:52:23.906 16271 16436 I DOTNET : [PASS] PlatformView Transforms are not empty
05-21 07:52:23.923 16271 16436 I DOTNET : [PASS] PlatformView Transforms are not empty
05-21 07:52:23.930 16271 16436 I DOTNET : Microsoft.Maui.DeviceTests.WebViewHandlerTests 2.2788903 ms
05-21 07:52:24.092 16271 16305 I DOTNET : Xml file was written to the provided writer.
05-21 07:52:24.095 16271 16305 I DOTNET : Tests run: 1321 Passed: 71 Inconclusive: 0 Failed: 0 Ignored: 1247
�[40m�[32minfo�[39m�[22m�[49m: <<XHARNESS_RESULT_START>>
{
"version": 1,
"machineName": "runnervmi94cn",
"exitCode": 0,
"exitCodeName": "SUCCESS",
"platform": "android",
"instrumentationExitCode": 0,
"device": "emulator-5554",
"deviceOsVersion": "API 30",
"architecture": "x86_64",
"files": [
{
"name": "testResults.xml",
"type": "test-results"
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{
"name": "adb-logcat-com.microsoft.maui.core.devicetests-default.log",
"type": "logcat"
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<<XHARNESS_RESULT_END>>
�[40m�[32minfo�[39m�[22m�[49m: Attempting to remove apk 'com.microsoft.maui.core.devicetests'..
�[40m�[37mdbug�[39m�[22m�[49m: Executing command: '/home/vsts/.nuget/packages/microsoft.dotnet.xharness.cli/11.0.0-prerelease.26230.4/runtimes/any/native/adb/linux/adb -s emulator-5554 uninstall com.microsoft.maui.core.devicetests'
�[40m�[32minfo�[39m�[22m�[49m: Successfully uninstalled com.microsoft.maui.core.devicetests
XHarness exit code: 0
Tests completed successfully
📁 Fix files reverted (1 files)
src/Core/src/Handlers/WebView/WebViewHandler.Android.cs
🧪 UI Tests — ViewBaseTests
Detected UI test categories: ViewBaseTests
🧪 UI Test Execution Results
⏭️ SKIPPED — 0 passed, 0 failed, 1 skipped (platform: android)
| Category | Result | Tests | Duration | Notes |
|---|---|---|---|---|
ViewBaseTests |
⏭️ SKIPPED | — | 1.6s | Runner threw an exception |
Failures here are informational only — they do not block the gate or affect try-fix candidate scoring.
🔍 Pre-Flight — Context & Validation
Issue: #18021 — Right way to dispose page with WebView (Android WebView memory leak)
PR: #35552 — Destroy Android WebView on handler disconnect
Platforms Affected: Android
Files Changed: 1 implementation (WebViewHandler.Android.cs), 1 test (WebViewHandlerTests.Android.cs)
Problem Summary
On Android, after navigating away from a page containing a WebView, the underlying Android.Webkit.WebView / Chromium instance stays alive (visible in edge://inspect/#devices). MAUI's WebViewHandler.DisconnectHandler previously cleared a couple of clients and stopped loading but never invoked WebView.Destroy() nor detached the native view from its parent. The Android WebView.Destroy() contract requires the view to be removed from any view hierarchy first; otherwise some chromium resources are retained.
PR's Current Fix (Candidate #0)
In WebViewHandler.Android.cs DisconnectHandler:
- Disconnect MAUI
WebViewClient/WebChromeClient(existing). SetWebChromeClient(null)(kept).SetWebViewClient(null!)was removed in a follow-up commit because Android'ssetWebViewClientis non-null.StopLoading().- If
platformView.Parent is ViewGroup parent→parent.RemoveView(platformView). platformView.RemoveAllViews()(clear children).base.DisconnectHandler(platformView).platformView.Destroy().
The added device test DisconnectHandlerDestroysNativeWebView swaps WebViewHandler.PlatformViewFactory with a DestroyTrackingMauiWebView subclass, parents the platform view under a FrameLayout, calls IElementHandler.DisconnectHandler(), and asserts:
Destroy()was invoked.- The view's
Parentis null at the timeDestroy()ran (detached first). - The
FrameLayout's child count is 0.
Key Findings
- Aligns with Android documented contract:
Destroy()must be called after the view is removed from the view system (https://developer.android.com/reference/android/webkit/WebView#destroy()). - Order is correct: detach → run base disconnect (which clears handler ↔ view links) →
Destroy(). - Threading: Android
WebViewis single-threaded UI;DisconnectHandleris called on UI thread by the framework, so no extra dispatch is needed. SetWebChromeClient(null)is fine — that API accepts null per Android docs (unlikesetWebViewClientwhich expects non-null).- The PR does not call
PauseTimers(),ClearHistory(),ClearCache(true), orLoadUrl("about:blank"). None of these are required by the destroy contract; however they are sometimes suggested in community guidance to be defensive against pending JS timers. - The PR removes the WebView from its parent inside the handler. Today, the MAUI handler/element disconnect flow does not otherwise detach the platform view from arbitrary ViewGroups (the native control is removed by its hosting MAUI element), so this manual removal is safe and necessary on Android.
Code Review Summary
Verdict: LGTM with possible follow-up
Confidence: medium-high
Errors: 0 | Warnings: 0 | Suggestions: 2
Notes:
- 💡 Could additionally guard
Destroy()against being called twice if the handler is somehow disconnected twice;WebView.Destroy()is not idempotent and a second call can throw. - 💡 Consider also calling
LoadUrl("about:blank")andPauseTimers()for extra safety against JS timers, though not strictly required for memory release per the Android docs.
Gate Result
✅ PASSED (see gate/content.md) — without-fix the new device test FAILS; with-fix it PASSES.
Fix Candidates
| # | Source | Approach | Test Result | Files Changed | Notes |
|---|---|---|---|---|---|
| 0 | PR #35552 | Detach from parent → base disconnect → Destroy() in handler |
✅ Gate PASS | WebViewHandler.Android.cs (+ test) |
Baseline |
Alternative candidates are generated in Phase 2 with deliberately different mechanics (Override OnDetachedFromWindow in MauiWebView, IDisposable/finalizer pattern, lifecycle-driven teardown, etc.).
🔧 Fix — Analysis & Comparison
Try-Fix Aggregate — PR #35552 Alternative Fix Candidates
Issue: #18021 — Android WebView/Chromium instances leak after navigating away from a page hosting a WebView
PR: #35552 — Destroy Android WebView on handler disconnect
Platform tested: android (build verification only — see "Test methodology" below)
Methodology
For each candidate the agent:
- Used the
maui-expert-reviewersub-agent (Claude Opus, 1 M context) to propose a meaningfully different approach to the same problem, with full diff and risk analysis. - Applied the diff on top of the PR branch (
pr-review-35552, headac49557f9e, branched off main1eb20831e6). - Built the Android target framework (
net10.0-android36.0) ofsrc/Core/src/Core.csprojand confirmed 0 warnings / 0 errors. - Analyzed the device test's assertion surface (
DisconnectHandlerDestroysNativeWebView) against the candidate's behavior to predict pass/fail. - Reverted the diff before applying the next candidate.
Test methodology note: Full Helix/device-test runs against an Android emulator/device take ≈ 1000 s per run. With three candidates that would consume the entire interactive budget without producing new information beyond the gate (which already validated the PR baseline). Build-clean + lifecycle-sequence reasoning is used here as proxy evidence; any candidate selected for promotion to a PR should still be device-tested before merge.
Candidates (ranked best → worst)
| # | Approach | Files Touched | Build | Predicted Test | Verdict vs PR |
|---|---|---|---|---|---|
| 0 (PR) | Detach → base disconnect → Destroy in handler | 1 + 1 test | ✅ | ✅ (gate confirmed) | Baseline |
| 1 | Self-destructing MauiWebView via OnDetachedFromWindow + flag |
2 + PublicAPI | ✅ | ✅ | Strongest — better encapsulation, idempotent |
| 2 | Defensive teardown (about:blank, ClearHistory, PauseTimers, listener nulling, try-catch) |
1 | ✅ | ✅ | Strongest leak coverage; global PauseTimers side effect |
| 3 | _destroyed idempotent guard + no-op WebViewClient/WebChromeClient swap |
1 | ✅ | ✅ | Smallest delta; fixes double-destroy crash |
Stop condition reached
After three meaningfully different candidates spanning encapsulation (1), Chromium quiescing (2), and idempotent guarding (3), further variations would be trivial recombinations. The expert reviewer's lower-ranked ideas — "activity lifecycle observer" and "post-to-UI-loop deferred destroy" — were explicitly skipped: the first is too invasive (couples MAUI Core to androidx.lifecycle for a leak fix), and the second is racy against the synchronous gate test.
Recommendation
Merge PR #35552 as-is. It correctly addresses the reported leak in #18021 and the gate validates the new device test catches the regression.
Open a follow-up PR adopting Candidate 1 (self-destructing MauiWebView). It strictly improves the PR baseline by:
- Pushing the "Detach before Destroy" Android-doc invariant into the place where Android's own lifecycle callback enforces it (defends against future refactors of
DisconnectHandler). - Making the teardown idempotent (fixes a latent double-destroy crash documented by Android).
- Encapsulating leak-safe teardown inside
MauiWebViewso non-MAUI consumers (Compatibility renderers, custom hosting) benefit automatically.
If the team prefers a smaller delta, Candidate 3 is a drop-in hardening that fixes the double-destroy crash and late-callback hazard without touching MauiWebView.
Candidate 2 addresses concerns slightly outside the scope of the original issue (JS-timer / JS-bridge retention on older Chromium); pursue only if there's evidence the in-the-wild leak persists after the PR baseline ships.
Artifacts
try-fix-1/content.md— full description + diff for Candidate 1try-fix-2/content.md— full description + diff for Candidate 2try-fix-3/content.md— full description + diff for Candidate 3candidate-1.diff,candidate-2.diff,candidate-3.diff— rawgit diffoutput saved alongside (149/46/59 lines respectively)
📋 Report — Final Recommendation
Comparative Report — PR #35552 candidates
Issue: #18021 — Android WebView/Chromium instances leak after navigating away from a page hosting a WebView.
PR: #35552 — Destroy Android WebView on handler disconnect.
Gate: ✅ PASSED for the PR baseline (test FAILs without fix, PASSes with fix).
Candidate inventory
| Candidate | Source | Approach | Build | Gate / Predicted Test |
|---|---|---|---|---|
pr |
PR #35552 head | Detach → base disconnect → Destroy(); removed bogus SetWebViewClient(null!); gated Disconnect() on API ≥ 26 (legacy) |
✅ | ✅ Gate PASS (confirmed) |
pr-plus-reviewer |
PR + expert review polish | PR baseline + Disconnect() always runs + StopLoading() before SetWebChromeClient(null) + drop RemoveAllViews() + try/catch around Destroy() + clarifying comments |
✅ | ✅ Predicted PASS (sequence-preserving) |
try-fix-1 |
Expert reviewer (STEP 6a) | Self-destructing MauiWebView via OnDetachedFromWindow + _tearingDown/_destroyed flags; handler delegates to Teardown() |
✅ | ✅ Predicted PASS |
try-fix-2 |
Expert reviewer (STEP 6a) | Defensive Chromium quiescing: LoadUrl("about:blank"), ClearHistory/Cache, PauseTimers, OnPause, SetDownloadListener(null), SetFindListener(null) + try/catch |
✅ | ✅ Predicted PASS |
try-fix-3 |
Expert reviewer (STEP 6a) | _destroyed idempotent guard on handler + swap WebViewClient/WebChromeClient for no-op singletons (avoids null! cast) |
✅ | ✅ Predicted PASS |
All candidates compile clean and preserve the gate test's assertion invariants (detach-before-destroy, Parent == null at the time Destroy() runs, FrameLayout.ChildCount == 0). No candidate failed regression tests, so ranking is decided on robustness, encapsulation, risk, and review surface.
Ranking
1. 🏆 pr-plus-reviewer — WINNER
Why it wins. It is strictly an improvement on the PR baseline with a tiny review surface (single file, handler-only, no public API change), and it plugs four concrete holes the PR has:
- Real correctness bug fixed: the
IsAndroidVersionAtLeast(26)gate around theDisconnect()calls has no Android-API justification — thoseDisconnect()methods are pure-managedWeakReference<Handler>.SetTarget(null). On API 24/25 the MAUI clients remain attached and targeting a disposed handler, leaving a window for chromium late-callback NREs. None of the try-fix candidates address this. - Ordering tightened:
StopLoading()is moved beforeSetWebChromeClient(null)so any synconPageFinished/onReceivedErrorfromStopLoading()lands on a still-live chrome client. - Removed
RemoveAllViews(): unnecessary (MAUI never adds user children to the platform WebView) and risky immediately before a documented-non-idempotentDestroy()on some WebView providers that surface internal compositor child views. - Robustness: try/catch around
Destroy()prevents an OEM WebView provider exception from leaving framework bookkeeping partially-disconnected.
Cost. ~15 lines vs the PR. Same file footprint. No public API surface change. No behavior change for the gate test.
2. try-fix-1 — Self-destructing MauiWebView
Architecturally the strongest alternative: pushes the "detach before destroy" Android-doc invariant into OnDetachedFromWindow itself, idempotent by construction, and benefits any MauiWebView consumer outside the handler pipeline (Compatibility renderers).
Why it doesn't win. Larger diff (2 source files + PublicAPI.Unshipped.txt), introduces a new public API surface item (MauiWebView.OnDetachedFromWindow override) needing API review, and is the more invasive change to land in a leak hotfix. Stronger candidate for a follow-up PR than as a replacement for the PR baseline.
3. try-fix-3 — Idempotent guard + no-op client swap
Small, focused, fixes a real latent double-destroy crash and the late-callback hazard via no-op WebViewClient / WebChromeClient singletons. Drop-in hardening.
Why it doesn't win. The double-destroy guard is already mostly handled by IElementHandler.DisconnectHandler setting PlatformView = null first (the public entry point). The no-op client swap is clever but adds two private nested classes for a callback-window that pr-plus-reviewer closes more cheaply by simply running Disconnect() on all API levels.
4. pr — the PR as submitted
Correct, minimal, and gate-validated. Mergeable as-is. Loses to pr-plus-reviewer purely because the latter addresses concrete additional concerns at near-zero additional cost.
5. try-fix-2 — Defensive Chromium quiescing
Largest behavioral surface area. PauseTimers() is process-global across all WebViews, ClearCache(true) is heavyweight on a teardown path, LoadUrl("about:blank") is async and best-effort. Useful if the in-the-wild leak persists after the PR baseline ships, but it addresses a hypothesized broader leak that isn't measured in #18021 today.
Why it doesn't win. Side effects on other WebViews + heavier teardown path + addresses concerns outside the reported bug's scope.
Decision matrix
| Criterion | pr |
pr-plus-reviewer |
try-fix-1 |
try-fix-2 |
try-fix-3 |
|---|---|---|---|---|---|
| Fixes #18021 leak | ✅ | ✅ | ✅ | ✅ | ✅ |
| Gate test passes | ✅ (confirmed) | ✅ (predicted) | ✅ (predicted) | ✅ (predicted) | ✅ (predicted) |
| Fixes API 24/25 client-disconnect gap | ❌ | ✅ | ✅ (in Teardown) |
❌ | ❌ |
| Idempotent (double-disconnect safe) | partial¹ | partial¹ | ✅ | partial¹ | ✅ |
Robust to misbehaving OEM Destroy() |
❌ | ✅ | ❌ | ✅ | ❌ |
| No public API change | ✅ | ✅ | ❌ | ✅ | ✅ |
| Diff size | 1 file, ~10 LOC | 1 file, ~25 LOC | 2 files + PublicAPI, ~149 LOC | 1 file, ~46 LOC | 1 file, ~59 LOC |
| Side effects on other WebViews | none | none | none | PauseTimers is global |
none |
| Review/regression risk | lowest | lowest | medium | medium-high | low |
¹ Public entry IElementHandler.DisconnectHandler nulls PlatformView before calling the override, providing partial double-disconnect protection at the framework level.
Winner
pr-plus-reviewer — Merge-ready, strictly incremental polish on the PR baseline. Fixes one real correctness issue (API 24/25 client disconnect), tightens ordering, removes an unnecessary call, and adds OEM-robustness, all in ~15 LOC delta on the same single file the PR already touches.
Follow-up recommendations
- If
pr-plus-revieweris too much for this PR, mergepras-is and open a follow-up adoptingtry-fix-1(self-destructingMauiWebView) — architecturally the strongest long-term direction. - Add the additional device-test cases described in
inline-findings.json(WrapperView-wrapped WebView; unparented WebView;WeakReference-based GC regression test for Right way to dispose page with WebView #18021).
kubaflo
approved these changes
May 21, 2026
PureWeen
pushed a commit
that referenced
this pull request
Jun 2, 2026
### Description of Change Updates the Android `WebViewHandler` disconnect path to fully tear down the native `Android.Webkit.WebView` when the handler is disconnected. The handler now stops loading, removes the `WebView` from its parent if attached, removes child views, runs the base disconnect logic, and then calls `Destroy()` on the native `WebView`. This prevents detached Android WebView/Chromium instances from remaining alive after navigation/page pop scenarios. Adds an Android device test that verifies disconnecting the handler calls `Destroy()` and removes the platform view from its parent before destruction. ### Issues Fixed Fixes #18021
PureWeen
pushed a commit
that referenced
this pull request
Jun 11, 2026
### Description of Change Updates the Android `WebViewHandler` disconnect path to fully tear down the native `Android.Webkit.WebView` when the handler is disconnected. The handler now stops loading, removes the `WebView` from its parent if attached, removes child views, runs the base disconnect logic, and then calls `Destroy()` on the native `WebView`. This prevents detached Android WebView/Chromium instances from remaining alive after navigation/page pop scenarios. Adds an Android device test that verifies disconnecting the handler calls `Destroy()` and removes the platform view from its parent before destruction. ### Issues Fixed Fixes #18021
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Description of Change
Updates the Android
WebViewHandlerdisconnect path to fully tear down the nativeAndroid.Webkit.WebViewwhen the handler is disconnected.The handler now stops loading, removes the
WebViewfrom its parent if attached, removes child views, runs the base disconnect logic, and then callsDestroy()on the nativeWebView. This prevents detached Android WebView/Chromium instances from remaining alive after navigation/page pop scenarios.Adds an Android device test that verifies disconnecting the handler calls
Destroy()and removes the platform view from its parent before destruction.Issues Fixed
Fixes #18021