Maui Android web handler

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Maui Android web handler

Jerry Bonetti 5

I am trying to create a webview handler for android in order to test calling a local web server with a self signed cert. I have seen numerous examples of how to create a client for WebView to capture the OnReceivedSslError methods but it is never called.

I am using Visual Studio 2026 with net 10.

I create the handler the client and the add handler logic in the startup.

Handler is initialized but OnReceivedSslError is never called when I create a WebView instance.

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Answer 1

Hi @Jerry Bonetti ,

Thanks for reaching out.

I took a closer look at what you described. If your custom handler is initializing but OnReceivedSslError is never being called, that usually means one of two things: either Android isn’t actually seeing an SSL error, or your custom WebViewClient isn’t the one being used by the WebView.

The first thing I’d verify is whether the certificate is truly untrusted on the device/emulator. If the self-signed certificate has been installed or trusted through the Android network security configuration, the WebView won’t treat it as an error, and if there’s no SSL error, OnReceivedSslError will never fire. A quick way to confirm this is to browse to the same URL in Chrome on the device and see whether it shows a certificate warning.

If you do see a warning in Chrome but still don’t hit OnReceivedSslError in your app, the next likely cause is that your custom WebViewClient isn’t actually attached to the native Android WebView. In .NET MAUI (especially with .NET 10), it’s important to explicitly set the client inside the handler’s ConnectHandler method, for example:

Override ConnectHandler(Android.Webkit.WebView platformView)
Call platformView.SetWebViewClient(new YourCustomClient())

Even if the handler itself is registered in MauiProgram, MAUI can still assign its own default client unless you explicitly replace it at the platform view level. That’s often the missing piece.

Also make sure you’re testing with an https:// endpoint and not http://localhost. If SSL isn’t actually being negotiated, there’s nothing for Android to validate.

Hope this helps! If my answer was helpful - kindly follow the instructions here so others with the same problem can benefit as well.

Jerry Bonetti 5 Reputation points

2026-02-18T10:44:07.58+00:00

Thank you for the input.

Yes it is a local self signed cert and url is https... which gives the ssl error on browser so I know for sure it gives ssl cert error. In fact I had to create a handler for the windows maui version.

What I decided to do this morning is search on this forum and I found a solution.

What I was doing is creating a custom handler and view client outlined in many examples out there and then loading it in my startup using builder.ConfigureMauiHandlers. None of those variations called my custom web view client. Then on this forum I found the following approach and added it to my startup and now it works:

#if ANDROID

Microsoft.Maui.Handlers.WebViewHandler.Mapper.AppendToMapping("MyCustomization", (handler, view) => { if (view is InsecureWebView) { InsecureWebView customWebView = view as InsecureWebView; handler.PlatformView.SetWebViewClient(new CustomWebViewClient()); } });

#endif

My webclient simply overrides the OnReceivedSslError

public class CustomWebViewClient : WebViewClient { public override void OnReceivedSslError(global::Android.Webkit.WebView view, SslErrorHandler handler, SslError error) { handler.Proceed(); } }
Jack Dang (WICLOUD CORPORATION) 14,955 Reputation points Microsoft External Staff Moderator

2026-02-18T10:55:40.55+00:00

Hi @Jerry Bonetti ,

Thanks for your feedback.

Kindly follow the instructions here so others with the same problem as you can benefit as well. Thank you!

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