Troubleshooting-Android.md

July 4, 2026 · View on GitHub

Troubleshooting (Android)

Build fails due to duplicate classes (measurement / compose / etc.)

Symptoms

  • Type ... is defined multiple times
  • JAVA0000: Compilation failed
  • Conflicts after adding another library (for example Firebase) or after moving to .NET 10.

Fix / mitigation

  • Clean aggressively:
    • Clean the solution
    • Delete bin and obj
    • Rebuild
  • If you hit duplicate Compose annotation classes on .NET 10 (issues #67 and #80, e.g. Type androidx.compose.runtime.StableMarker is defined multiple times): the root cause is Xamarin.GooglePlayServices.Ads.Lite 124.0.0.4 (shipped with plugin 3.0.2 and earlier) transitively pulling both the .Android and .Jvm variants of Xamarin.AndroidX.Compose.Runtime.Annotation. This is fixed in Xamarin.GooglePlayServices.Ads.Lite 124.0.0.5+, which plugin versions after 3.0.2 reference. On plugin 3.0.2 or earlier, either update the Ads SDK directly in your app project (verified fix):
<ItemGroup Condition="'$(TargetFramework)' == 'net10.0-android'">
	<PackageReference Include="Xamarin.GooglePlayServices.Ads.Lite" Version="124.0.0.6" />
</ItemGroup>

or exclude the JVM variant (also verified):

<ItemGroup Condition="'$(TargetFramework)' == 'net10.0-android'">
	<PackageReference Include="Xamarin.AndroidX.Compose.Runtime.Annotation.Jvm" Version="1.10.0.1" ExcludeAssets="all" />
</ItemGroup>

Note: updating your app's Microsoft.Maui.Controls version does not fix this — the duplicate variants come from the Ads SDK's dependency graph, not MAUI's.

  • If you use Firebase and hit duplicate Google measurement classes (see issues #29 and #55, e.g. Type com.google.android.gms.internal.measurement.zzbm is defined multiple times): the Google "measurement" classes ship in both Xamarin.GooglePlayServices.Measurement.* (pulled in by this plugin via Xamarin.GooglePlayServices.Ads.Lite) and Xamarin.Firebase.Analytics (pulled in by Plugin.Firebase). The build only works when the whole family resolves to the same Google release train. Align them by referencing Xamarin.Firebase.Analytics directly in your app at the version matching the resolved Xamarin.GooglePlayServices.Measurement.Base (check obj/project.assets.json). Verified with Plugin.Firebase 4.2.1 and Xamarin.GooglePlayServices.Ads.Lite 124.0.0.6:
<ItemGroup Condition="'$(TargetFramework)' == 'net10.0-android'">
	<PackageReference Include="Xamarin.Firebase.Analytics" Version="123.2.0.1" />
</ItemGroup>

Note: enabling MultiDex or switching to d8/r8 does not fix this — d8/r8 fail on duplicate type definitions rather than deduplicating them.

  • #29 (duplicate measurement classes when combined with Firebase)
  • #67 (duplicate Compose runtime annotation classes on .NET 10)
  • #80 (duplicate Compose annotation classes in Release builds on plugin 3.0.2)

AndroidManifest namespace warnings on .NET 10 / API 35+

Symptoms

  • Warnings like:
    • Namespace 'com.google.android.gms.ads' is used in multiple modules and/or libraries

Fix / mitigation

Make sure your app explicitly sets a minimum Android platform version compatible with Google Play Services. For .NET 10, set SupportedOSPlatformVersion to 23:

<PropertyGroup Condition="'$(TargetFramework)' == 'net10.0-android'">
	<SupportedOSPlatformVersion>23.0</SupportedOSPlatformVersion>
</PropertyGroup>
  • #68 (namespace warnings when min platform is too low)

NU1608 warnings: "Detected package version outside of dependency constraint"

Symptoms

Building an app that references the plugin emits warnings like:

warning NU1608: Detected package version outside of dependency constraint: Xamarin.AndroidX.Fragment.Ktx 1.8.8.1 requires Xamarin.AndroidX.Fragment (>= 1.8.8.1 && < 1.8.9) but version Xamarin.AndroidX.Fragment 1.8.9.1 was resolved.

Root cause

Google Play Services (pulled in via Xamarin.GooglePlayServices.Ads.Lite) depends on older Xamarin.AndroidX.*.Ktx packages, whose declared upper bounds don't admit the newer AndroidX base packages that .NET MAUI resolves. The pairs are compatible in practice — NU1608 is a warning, not an error — but the noise is legitimate to want gone.

Fix / mitigation

Reference the Ktx packages directly in your app project at versions aligned with the resolved base packages. Verified to produce zero NU1608 warnings with Plugin.AdMob 10.0.80-beta.7 and .NET MAUI 10.0.80 (the sample apps carry the same set):

<ItemGroup Condition="'$(TargetFramework)' == 'net10.0-android'">
	<PackageReference Include="Xamarin.AndroidX.Fragment.Ktx" Version="1.8.9.4" />
	<PackageReference Include="Xamarin.AndroidX.Collection.Ktx" Version="1.6.0.1" />
	<PackageReference Include="Xamarin.AndroidX.Activity.Ktx" Version="1.13.0.1" />
	<PackageReference Include="Xamarin.AndroidX.Lifecycle.ViewModel.Ktx" Version="2.11.0.1" />
	<PackageReference Include="Xamarin.AndroidX.SavedState.SavedState.Ktx" Version="1.5.0.1" />
	<PackageReference Include="Xamarin.AndroidX.Lifecycle.Runtime.Ktx.Android" Version="2.11.0.1" />
	<PackageReference Include="Xamarin.AndroidX.Lifecycle.Runtime.Ktx" Version="2.11.0.1" />
	<PackageReference Include="Xamarin.AndroidX.Lifecycle.Process" Version="2.11.0.1" />
</ItemGroup>

If new NU1608 warnings appear after a MAUI or plugin update, adjust the pinned versions to match the newly resolved base packages (check the warnings themselves or obj/project.assets.json).

  • #82 (NU1608 dependency constraint warnings)

Full-screen test ads fail with "no fill" on emulators (banners work)

Symptoms

  • Interstitial, rewarded, rewarded interstitial, and app open test ads fail to load with Ad failed to load : 3 ("No fill.") on an Android emulator, while banner test ads load and render fine.
  • Consent is granted and AdConfig.UseTestAdUnitIds = true, so a fill is expected every time.
  • The full LoadAdError response shows the demo campaign was served, but the adapter failed instantly:
"Ad Source Instance Name": "[DO NOT EDIT] Publisher Test Interstitial",
"Ad Error": { "Code": 0, "Message": "Internal error.", ... },
"Latency": 0

Root cause

The emulator is running with software GPU rendering (-gpu swiftshader_indirect, or "Graphics: Software" in the AVD settings). Full-screen ad creatives are pre-rendered at load time and fail with an internal error without hardware acceleration. The SDK surfaces this as a generic no-fill. Banner ads are not affected, which makes it look like an ad-serving or plugin problem when it is not.

Fix / mitigation

  • Start the emulator with hardware graphics acceleration: emulator -avd <name> -gpu host, or set Graphics: Hardware in the AVD settings in Android Studio.
  • To see the underlying error instead of a bare "no fill", subscribe to OnAdFailedToLoad on the ad or ad service and log the message.
  • Physical devices are unaffected.

Native test ads fail on emulators without the Play Store

Native test ads fail with Ad failed to load : 0 and Incorrect native ad response. Click actions were not properly specified on Google APIs emulator images: the native demo campaign serves app-install creatives whose click actions need the Play Store. Use a Google Play system image. See Troubleshooting-Native-ads for details.

Runtime errors on older Android versions

Symptoms

  • Java.Lang.NoSuchMethodError mentioning getDisplay()
  • Analyzer warnings like 'Context.Display' is only supported on: 'android' 30.0 and later.

Fix / mitigation

  • Update to the latest plugin version.
  • If you still reproduce it, capture the exception + target Android version and report it.
  • #40 (older Android compatibility / getDisplay() errors)