Fix for BlazorWebView Back Navigation Issues on Android 13+ After Predictive Back Gesture Changes by SuthiYuvaraj · Pull Request #33213 · dotnet/maui

SuthiYuvaraj · 2025-12-18T13:54:58Z

Issue Description

BlazorWebView back navigation stopped working in .NET 10 on Android. When the user presses the back button while viewing a BlazorWebView with navigable history, the entire page is popped instead of navigating back within the WebView content

RootCause

The AndroidLifecycle.OnBackPressed lifecycle event system introduced for Android 13+ predictive back gesture support intercepts back navigation. Since BlazorWebView doesn't register a handler to check WebView.CanGoBack(), the system pops the entire page instead of allowing the WebView to navigate its internal history first, breaking the back navigation behavior that worked in .NET 9.

Description of Change

PR #32461 introduced distributed back navigation handling for Android 13+ predictive back gesture support. This PR extends that implementation to include BlazorWebView

BlazorWebViewHandler.Android.cs:

Added an AndroidLifecycle.OnBackPressed handler in ConnectHandler. The handler checks WebView.CanGoBack() to determine whether the BlazorWebView maintains internal navigation history. If history exists, it calls WebView.GoBack() and returns true, ensuring the user navigates backwards within the WebView instead of closing the page. If no internal history exists, it returns false, allowing the standard MAUI navigation stack to handle the back action.

LifecycleEventService.cs:

Added RemoveEvent<TDelegate> method to properly cleanup lifecycle event handlers and prevent memory leaks when handlers are disconnected.

Issues Fixed

Fixes #32767

Tested the behaviour on the following platforms

Android
Windows
iOS
Mac

Output Screenshot

Before Issue Fix	After Issue Fix
Screen.Recording.2025-12-18.at.7.21.48.PM.mov	Screen.Recording.2025-12-18.at.7.13.08.PM.mov

Copilot

Pull request overview

This PR fixes BlazorWebView back navigation on Android 13+ by implementing an OnBackPressed lifecycle event handler that checks for WebView navigation history before allowing page navigation. The fix extends the predictive back gesture support introduced in PR #32461 to include BlazorWebView components, and adds a cleanup mechanism for lifecycle event handlers to prevent memory leaks.

Key Changes

Adds OnBackPressed handler registration in BlazorWebViewHandler.ConnectHandler that checks WebView.CanGoBack() before allowing page pop
Implements RemoveEvent method in LifecycleEventService to support proper handler cleanup in DisconnectHandler
Updates public API surface to track the new ConnectHandler override

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 7 comments.

File	Description
src/Core/src/LifecycleEvents/LifecycleEventService.cs	Adds internal RemoveEvent method to enable lifecycle event handler cleanup
src/BlazorWebView/src/Maui/Android/BlazorWebViewHandler.Android.cs	Implements ConnectHandler/DisconnectHandler overrides to register/unregister OnBackPressed handler for WebView back navigation
src/BlazorWebView/src/Maui/PublicAPI/net-android/PublicAPI.Unshipped.txt	Tracks new ConnectHandler override as public API surface change

src/Core/src/LifecycleEvents/LifecycleEventService.cs

src/BlazorWebView/src/Maui/Android/BlazorWebViewHandler.Android.cs

src/Core/src/LifecycleEvents/LifecycleEventService.cs

Copilot · 2025-12-18T15:39:05Z

src/BlazorWebView/src/Maui/Android/BlazorWebViewHandler.Android.cs

+				var lifecycleService = MauiContext.Services.GetService<ILifecycleEventService>();
+				if (lifecycleService is LifecycleEventService concreteService)
+				{
+					concreteService.RemoveEvent(nameof(AndroidLifecycle.OnBackPressed), _onBackPressedHandler);
+					_onBackPressedHandler = null;
+				}


The same cast pattern (ILifecycleEventService to LifecycleEventService) is repeated in both ConnectHandler and DisconnectHandler. Consider extracting this to a helper method or property to reduce code duplication and make the intent clearer. For example, a private method like TryGetLifecycleEventService() that returns the concrete service or null.

StephaneDelcroix

✅ APPROVE

Summary: PR correctly fixes BlazorWebView back navigation on Android 13+ by registering an OnBackPressed lifecycle event handler.

What the PR Does

Adds OnBackPressed handler in ConnectHandler that checks CanGoBack() before navigating
Handles multiple BlazorWebView instances with visibility/focus checks (IsAttachedToWindow, HasWindowFocus)
Uses WeakReference to prevent memory leaks
Adds RemoveEvent to LifecycleEventService for proper cleanup
Cleans up handler in DisconnectHandler to prevent leaks

Tests Added

I've added Device Tests to verify the fix:

BlazorWebViewRegistersOnBackPressedHandler - Verifies handler is registered when BlazorWebView connects
BlazorWebViewCleansUpOnBackPressedHandlerOnDisconnect - Verifies cleanup on disconnect

Location: src/BlazorWebView/tests/DeviceTests/Elements/BlazorWebViewTests.BackNavigation.cs

Alternative Approaches Considered

Override OnKeyDown: Won't work with Android 13+ predictive back gestures
Use AndroidX OnBackPressedDispatcher directly: Bypasses MAUI's existing architecture
PR's approach is optimal - integrates with MAUI's lifecycle event system

Minor Notes (Non-blocking)

RemoveEvent kept internal (acceptable, would require API review for public)
Thread-safety matches existing pattern in LifecycleEventService

Confidence: High - PR follows MAUI's established patterns and addresses all edge cases.

rmarinho · 2026-01-11T11:06:17Z

/azp run maui-pr-uitests

azure-pipelines · 2026-01-11T11:06:28Z

Azure Pipelines successfully started running 1 pipeline(s).

rmarinho · 2026-01-11T11:06:39Z

/azp run maui-pr-devicetests

azure-pipelines · 2026-01-11T11:06:52Z

Azure Pipelines successfully started running 1 pipeline(s).

erva0008 · 2026-01-12T11:53:32Z

@StephaneDelcroix
Hello Stephane, I tried your PR and found a possible problem.
Can you have a look at my video from today at:
#32767 (comment)

erva0008 · 2026-01-15T15:29:40Z

@SuthiYuvaraj Did you see my comment/videos in the linked issue at
#32767 (comment)

PureWeen

#33213 (comment)

SubhikshaSf4851 · 2026-01-20T13:50:08Z

@PureWeen The issue where the back button immediately exited the app instead of navigating within the BlazorWebView is now fixed.

erva0008 · 2026-01-20T15:08:44Z

I have tested the artifacts locally on my computer from @SubhikshaSf4851 's fix.
I can confirm that it now works for me.
Both "swiping" backwards and the button press navigates correctly "inside" the Blazor application until it's in the root, and then finally closing the app (like expected)⭐

PureWeen · 2026-01-22T00:15:42Z

/rebase

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Tests verify that BlazorWebViewHandler on Android: 1. Registers OnBackPressed lifecycle event handler in ConnectHandler 2. Properly cleans up the handler in DisconnectHandler Related to: dotnet#32767

…dictive Back Gesture Changes (#33213)  ### Issue Description BlazorWebView back navigation stopped working in .NET 10 on Android. When the user presses the back button while viewing a BlazorWebView with navigable history, the entire page is popped instead of navigating back within the WebView content ### RootCause The AndroidLifecycle.OnBackPressed lifecycle event system introduced for Android 13+ predictive back gesture support intercepts back navigation. Since BlazorWebView doesn't register a handler to check WebView.CanGoBack(), the system pops the entire page instead of allowing the WebView to navigate its internal history first, breaking the back navigation behavior that worked in .NET 9. ### Description of Change PR #32461 introduced distributed back navigation handling for Android 13+ predictive back gesture support. This PR extends that implementation to include BlazorWebView **BlazorWebViewHandler.Android.cs:** Added an `AndroidLifecycle.OnBackPressed` handler in ConnectHandler. The handler checks `WebView.CanGoBack()` to determine whether the BlazorWebView maintains internal navigation history. If history exists, it calls `WebView.GoBack()` and returns true, ensuring the user navigates backwards within the WebView instead of closing the page. If no internal history exists, it returns false, allowing the standard MAUI navigation stack to handle the back action. **LifecycleEventService.cs**: Added `RemoveEvent<TDelegate>` method to properly cleanup lifecycle event handlers and prevent memory leaks when handlers are disconnected. ### Issues Fixed Fixes #32767 ### Tested the behaviour on the following platforms - [x] Android - [ ] Windows - [ ] iOS - [ ] Mac ### Output Screenshot Before Issue Fix | After Issue Fix | |----------|----------| |<video width="300" height="150" alt="Before Fix" src="https://github.com/user-attachments/assets/0d6550f8-115a-4893-bb0c-ee24bff38378">|<video width="300" height="150" alt="After Fix" src="https://github.com/user-attachments/assets/49bf38a5-f7be-4790-8fbb-b29ab96b1ed3">| --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Co-authored-by: Stephane Delcroix <stephane@delcroix.org> Co-authored-by: Subhiksha Chandrasekaran <subhiksha.c@syncfusion.com>

dotnet-policy-service bot added the partner/syncfusion Issues / PR's with Syncfusion collaboration label Dec 18, 2025

vishnumenon2684 added the community ✨ Community Contribution label Dec 18, 2025

sheiksyedm added area-blazor Blazor Hybrid / Desktop, BlazorWebView platform/android labels Dec 18, 2025

SuthiYuvaraj changed the title ~~Fix for Back navigation different between .net 9 and .net 10 blazor hybrid~~ Fix for BlazorWebView Back Navigation Issues on Android 13+ After Predictive Back Gesture Changes Dec 18, 2025

sheiksyedm marked this pull request as ready for review December 18, 2025 15:27

Copilot AI review requested due to automatic review settings December 18, 2025 15:27

Copilot started reviewing on behalf of sheiksyedm December 18, 2025 15:28 View session

Copilot AI reviewed Dec 18, 2025

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jfversluis mentioned this pull request Dec 18, 2025

Back navigation different between .net 9 and .net 10 blazor hybrid #32767

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jfversluis added this to the .NET 10.0 SR3 milestone Dec 19, 2025

build-analysis bot mentioned this pull request Dec 19, 2025

System.TimeoutException #33245

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PureWeen added this to MAUI SDK Ongoing Dec 30, 2025

github-project-automation bot moved this to Todo in MAUI SDK Ongoing Dec 30, 2025

StephaneDelcroix previously approved these changes Jan 9, 2026

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github-project-automation bot moved this from Todo to Changes Requested in MAUI SDK Ongoing Jan 16, 2026

SubhikshaSf4851 dismissed StephaneDelcroix’s stale review via 5ade657 January 20, 2026 12:21

build-analysis bot mentioned this pull request Jan 20, 2026

"We stopped hearing from agent Azure Pipelines 32. Verify the agent machine is running and has a healthy network connection" dotnet/dnceng#1886

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3 tasks

PureWeen modified the milestones: .NET 10.0 SR3, .NET 10.0 SR4 Jan 21, 2026

SuthiYuvaraj and others added 7 commits January 22, 2026 00:16

fix-lifecycleEvent

356a931

Added RemoveEvent

1401aa7

remove publicAPI

2e08b43

Apply suggestion from @Copilot

90917be

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update BlazorWebViewHandler.Android.cs

14d7d07

Add Device Tests for BlazorWebView OnBackPressed handler registration

778ac31

Tests verify that BlazorWebViewHandler on Android: 1. Registers OnBackPressed lifecycle event handler in ConnectHandler 2. Properly cleans up the handler in DisconnectHandler Related to: dotnet#32767

Fix for back button navigation

4714458

github-actions bot force-pushed the fix-32767 branch from 5ade657 to 4714458 Compare January 22, 2026 00:16

PureWeen approved these changes Jan 22, 2026

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github-project-automation bot moved this from Changes Requested to Approved in MAUI SDK Ongoing Jan 22, 2026

PureWeen changed the base branch from main to inflight/current January 22, 2026 00:27

PureWeen merged commit b0fec72 into dotnet:inflight/current Jan 22, 2026
1 of 12 checks passed

github-project-automation bot moved this from Approved to Done in MAUI SDK Ongoing Jan 22, 2026

PureWeen mentioned this pull request Feb 3, 2026

February 2nd, Candidate #33779

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Issue Description

RootCause

Description of Change

Issues Fixed

Tested the behaviour on the following platforms

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Pull request overview

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✅ APPROVE

What the PR Does

Tests Added

Alternative Approaches Considered

Minor Notes (Non-blocking)

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