Xamarin.Android集成Auth0登录报错：net:ERR_UNKNOWN_URL_SCHEME

Hey Pavel, let's fix that net:ERR_UNKNOWN_URL_SCHEME error you're hitting with Auth0 in your Xamarin.Android app. I've dealt with this exact issue before—here's how to get your callback working properly, so your app can catch the Auth0 response instead of the browser trying to handle it:

1. Double-check your Auth0 Dashboard callback configuration #

First, head to your Auth0 Application settings and make sure your Allowed Callback URLs matches this format:
your_custom_scheme://{your_auth0_domain}/android/{your_app_package_name}/callback

For example, if your custom scheme is myapp, Auth0 domain is dev-abc123.auth0.com, and app package name is com.MyCompany.MyApp, the URL would be:
myapp://dev-abc123.auth0.com/android/com.MyCompany.MyApp/callback

This has to be exact—no typos, and the package name must match what's set in your Xamarin.Android project's properties (check Properties > Android Manifest > Package Name).

2. Add the Intent Filter to your AndroidManifest.xml #

The key fix here is telling Android that your app is responsible for handling URLs with your custom scheme. Open your AndroidManifest.xml and add this intent filter inside your MainActivity tag (keep your existing MAIN/LAUNCHER filter intact):

<activity android:name=".MainActivity">
    <!-- Existing MAIN/LAUNCHER intent filter -->
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>

    <!-- New Auth0 callback intent filter -->
    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <!-- Replace these values with your actual scheme, domain, and package path -->
        <data
            android:scheme="myapp"
            android:host="dev-abc123.auth0.com"
            android:pathPrefix="/android/com.MyCompany.MyApp/callback" />
    </intent-filter>
</activity>

The BROWSABLE category is critical here—it lets the browser send the URL to your app.

3. Update your MainActivity code to handle the callback #

Now you need to capture the incoming intent (whether the app was running in the background or cold-started) and pass it to the Auth0 SDK. Add these overrides to your MainActivity.cs:

using Auth0.OidcClient;

// ... your existing code

protected override void OnNewIntent(Intent intent)
{
    base.OnNewIntent(intent);
    // Pass the callback URL to Auth0 SDK if it exists
    if (intent?.Data != null)
    {
        Auth0Client.Instance.SendAuthorizationResponse(intent.Data.ToString());
    }
}

protected override void OnCreate(Bundle savedInstanceState)
{
    base.OnCreate(savedInstanceState);
    // ... your existing initialization code (SetContentView, etc.)

    // Handle callback if the app was cold-started
    if (Intent?.Data != null)
    {
        Auth0Client.Instance.SendAuthorizationResponse(Intent.Data.ToString());
    }
}

Also, make sure your Auth0 client initialization uses the exact same RedirectUri as you configured everywhere else:

var auth0Options = new Auth0ClientOptions
{
    Domain = "dev-abc123.auth0.com",
    ClientId = "your_auth0_client_id",
    RedirectUri = "myapp://dev-abc123.auth0.com/android/com.MyCompany.MyApp/callback",
    Scope = "openid profile email"
};

var auth0Client = new Auth0Client(auth0Options);

4. Avoid these common pitfalls #

• Don't use http/https for your scheme: Those are reserved for browsers—stick to a custom, unique scheme like myapp or yourappname.
• Case sensitivity matters: Your package name in the callback URL and manifest must match exactly (Android package names are case-sensitive).
• Test on a physical device or emulator with the app installed: If the app isn't installed, the browser can't route the callback to it, and you'll get the same error.
• If using Chrome Custom Tabs: Ensure the Auth0 SDK isn't configured to skip them, and your intent filter still covers the callback URL.

Once you make these changes, rebuild your app, test the flow, and the browser should properly redirect back to your app with the Auth0 code, no more ERR_UNKNOWN_URL_SCHEME errors.

内容的提问来源于stack exchange，提问作者pavel