xamarin-android-migration

name: xamarin-android-migration description: > WORKFLOW SKILL - Guide for migrating Xamarin.Android native apps to .NET for Android. Covers SDK-style project conversion, target framework monikers, MSBuild property changes, AndroidManifest.xml updates, NuGet dependency compatibility, Android binding library migration, Xamarin.Essentials in native apps, .NET CLI support, and platform-specific gotchas. USE FOR: "migrate Xamarin.Android", "upgrade Xamarin.Android to .NET", "Xamarin.Android to .NET for Android", "Android project migration", "Android binding library migration", "convert Android project to SDK-style", "AndroidSupportedAbis to RuntimeIdentifiers". DO NOT USE FOR: migrating Xamarin.Forms apps (use xamarin-forms-migration), migrating Xamarin.iOS apps (use xamarin-ios-migration), creating new MAUI apps from scratch (use feature-specific MAUI skills).

Xamarin.Android → .NET for Android Migration

For SDK-style project templates, MSBuild property tables, ABI conversion, namespace mappings, and CLI commands, see references/android-migration-api.md.

⚠️ Field-tested advice: Android migration is significantly harder than iOS. Expect more UI bugs, OEM-specific rendering differences, and issues not reproducible on emulators. Test on physical devices.

Migration Workflow

1. Create new .NET for Android project (dotnet new android)
2. Copy code and resources into the new project
3. Update MSBuild properties (see references/android-migration-api.md)
4. Update AndroidManifest.xml — remove <uses-sdk>, use csproj properties
5. Delete Resource.designer.cs (regenerated automatically)
6. Update NuGet dependencies
7. Migrate binding libraries (if applicable)
8. Replace Xamarin.Essentials with <UseMauiEssentials>true</UseMauiEssentials>
9. Handle encoding changes
10. Delete bin//obj/, build, test on physical devices

Strategy: Create a new project and copy code into it — don't edit the existing project file in place.

Critical Gotchas

⚠️ Remove <uses-sdk> from AndroidManifest.xml

<!-- ❌ Xamarin-style — causes build warnings/errors -->
<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="33" />

<!-- ✅ Use MSBuild properties instead -->
<TargetFramework>net8.0-android</TargetFramework>
<SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>

⚠️ Delete Resource.designer.cs

This file is auto-generated. Leftover copies from Xamarin cause duplicate symbol errors. Delete it — it will be regenerated.

⚠️ No .dll.config or .exe.config Support

.dll.config and <dllmap> are not supported in .NET Core. If your app uses System.Configuration.ConfigurationManager, migrate to appsettings.json or platform preferences.

⚠️ Essentials: Override Permissions in Every Activity

// ❌ Forgetting this → permissions silently fail
// ✅ Required in EVERY Activity that uses Essentials
public override void OnRequestPermissionsResult(
    int requestCode, string[] permissions, Permission[] grantResults)
{
    Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}

⚠️ AndroidManifest.xml Location Changed

AndroidManifest.xml is now in the project root (not Properties/). The SDK-style project finds it there by default.

Platform-Specific Pitfalls

NuGet Compatibility Note

Android is unique: packages targeting monoandroid still work on .NET for Android. No recompilation needed for most Android-specific packages. This is NOT true for iOS/Mac.

If no compatible version exists:

1. Recompile with .NET TFMs (if you own it)
2. Look for a preview .NET version
3. Replace with a .NET-compatible alternative

API Currency Warning

If your migrated app will also adopt .NET MAUI controls (e.g., via UseMaui), check the maui-current-apis skill for deprecated MAUI APIs to avoid (ListView, Frame, Device.*, etc.).

Quick Checklist

1. ☐ Created new .NET for Android project (dotnet new android)
2. ☐ Set TargetFramework to net8.0-android (or later)
3. ☐ Set SupportedOSPlatformVersion for minimum SDK
4. ☐ Converted AndroidSupportedAbis → RuntimeIdentifiers
5. ☐ Removed <uses-sdk> from AndroidManifest.xml
6. ☐ Copied source, resources, and project properties
7. ☐ Deleted Resource.designer.cs, bin/, obj/
8. ☐ Updated NuGet dependencies
9. ☐ Added UseMauiEssentials + Platform.Init() if using Essentials
10. ☐ Overridden OnRequestPermissionsResult in every Activity
11. ☐ Replaced MAndroidI18n with System.Text.Encoding.CodePages
12. ☐ Verified AOT settings (RunAOTCompilation, not AotAssemblies)
13. ☐ Tested on physical Android device(s) from multiple vendors