Here's an HTML formatted explanation of common causes for Android deep links not working: ```html

Troubleshooting Android Deep Links

Android deep links allow users to navigate directly to specific content within your app from a link (e.g., a website, an email, or another app). When these links fail to open your app as expected, it can be frustrating. Here's a breakdown of common reasons why your Android deep links might not be working:

Common Culprits:

1. Incorrect Manifest Configuration

The most frequent cause is a misconfiguration within your AndroidManifest.xml file. Check the following:

• <intent-filter> tags: Ensure you have an <intent-filter> block within the correct <activity> that is intended to handle the deep link.
• android:scheme: Verify the android:scheme attribute in your <data> tag matches the scheme in your deep link URL (e.g., http, https, or a custom scheme).
• android:host: The android:host attribute must precisely match the domain of your deep link URL. For example, if your URL is https://www.example.com/products/123, then android:host should be www.example.com.
• android:pathPrefix, android:pathPattern, android:path: Use these attributes to specify the specific path or pattern the deep link must follow. Make sure they align with the structure of your URLs. Choose only one of these path attributes and ensure it matches your needs. pathPrefix is for beginning matches, pathPattern uses regular expressions, and path is for exact string matches.
• android:autoVerify="true": For HTTPS schemes, this attribute is crucial. If set to true, Android will attempt to verify your app's association with the website, preventing other apps from intercepting the deep link. If verification fails, the link may not work correctly.
• android:exported="true": The activity handling the deep link must be exported.

2. Intent Filter Priority

If multiple activities could potentially handle the deep link, Android uses intent filter priority to determine which activity gets launched. If another app has a higher priority intent filter for the same URL scheme and host, it might intercept the link before your app. While explicitly setting priorities can be complex, ensure your filters are as specific as possible to avoid conflicts.

3. App Link Verification Issues (HTTPS only)

When using HTTPS deep links with android:autoVerify="true", Android relies on a Digital Asset Links file (assetlinks.json) hosted on your website to verify the association. Issues here can prevent the deep link from working:

• Missing assetlinks.json: The file must be located at /.well-known/assetlinks.json on your website.
• Incorrect JSON Syntax: The file's JSON structure must be valid and correctly formatted. Use a JSON validator to check for errors.
• Incorrect Package Name/SHA256 Fingerprint: The assetlinks.json file needs to include the correct package name and SHA256 fingerprint of your app's signing certificate. An incorrect fingerprint will cause verification to fail. Use keytool or the Gradle signing report to get the correct fingerprint.
• HTTPS Issues: Ensure your website uses a valid SSL certificate. Android might refuse to verify links on sites with invalid certificates.

4. Testing and Debugging

Thorough testing is crucial:

• Use adb: Employ adb commands to manually trigger the deep link intent. This bypasses browser handling and helps isolate issues with the manifest or app logic. Example: adb shell am start -W -a android.intent.action.VIEW -d "your_deep_link_url" your_package_name
• Clear App Data: Clear your app's data and cache regularly during testing, as cached verification results can sometimes interfere.
• Check Logcat: Use Logcat to monitor the system for errors or warnings related to intent resolution and app link verification.

5. Edge Cases

• Deferred Deep Linking: If the app is not yet installed, consider using a deferred deep linking solution (e.g., Firebase Dynamic Links). These handle the case where the link is clicked before the app is installed and redirect the user to the content after installation.
• URL Encoding: Ensure your URLs are properly encoded, especially if they contain special characters.

By systematically checking these potential problem areas, you can usually diagnose and fix why your Android deep links are not functioning correctly.

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