App links intent filters in assetlinks.json not working on Android

Solution 1:

For us it was Windows line endings!

Testing with "https://digitalassetlinks.googleapis.com/v1/statements:list?source.web.site=https://domain1:port&relation=delegate_permission/common.handle_all_urls" proved invaluable as it gave us an "Could not parse statement list (not valid JSON)" error which led us to the problem.

TIP: It was good to use the 'Save File' button in the Android Studio App Links Assistant instead of copying and pasting as we did - that way it generates the file itself and is guaranteed not to have this issue.

Solution 2:

There are some common pitfalls which you should check twice (I don't say that you did it wrong. It is just a check list):

1. Verify that the assetlinks.json is valid and stored accessible from https://example.com/.well-known/assetlinks.json to do that you need to visit https://digitalassetlinks.googleapis.com/v1/statements:list?source.web.site= https://example.com&relation=delegate_permission/common.handle_all_urls, there must be no errors.
2. If you link multiple domains at once, check that all domains are setup correctly as in step 1.
3. Make sure that those <intent-filters> which contain your <data> tags have the attribute android:autoVerify="true".

4. Verify that you have the required <meta-data> tag in your <application> tag:

   <meta-data
       android:name="asset_statements"
       android:resource="@string/asset_statements"/>
   

   The content of the asset_statements string must be:

   <string name="asset_statements" translatable="false">[{\"include\": \"https://example.com/.well-known/assetlinks.json\"}]
   

5. Use for debug also the release signing certificate (don't be scared you cannot upload it accidentally) use this in your build.gradle:

   buildTypes {
       release {
           minifyEnabled true
           proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
           signingConfig signingConfigs.release
       }
       debug {
           debuggable true
           signingConfig signingConfigs.release
       }
   }