Drop Mono support for mobile targets at .NET 11 GA #5553

Background

.NET 11 makes CoreCLR the default runtime for Android, iOS and MacCatalyst. Mono is not removed in the pre-releases: <UseMonoRuntime>true</UseMonoRuntime> is documented as an opt-back in .NET MAUI moves to CoreCLR in .NET 11.

Our reading is that this escape hatch exists for the .NET 11 pre-release period, and that dropping Mono for mobile is still planned for .NET 11 GA. Raised by @dartasen in #5529 (comment) and discussed in #5529 (comment).

So #5529 keeps Mono coverage for the pre-releases. This issue is the reminder to remove it at GA.

Current state on the preview 7 SDK

UseMonoRuntime=true alone fails on mobile TFMs:

error NETSDK1242: Building Android projects with the Mono runtime is not supported in .NET 11.0
and later. Use the CoreCLR runtime or target .NET 10.0.

The SDK's own _DisableCheckForUnsupportedMonoMobileRuntime=true turns that check off, and the Mono runtime packs still ship, so the result is a genuine Mono build — verified on the device test app:

• net11.0-android37.0 → libmonosgen-2.0.so, libmonodroid.so, no libcoreclr.so
• net11.0-ios26.5 → libmonosgen-2.0.dylib and libxamarin-dotnet.dylib (not the -coreclr variant), no libcoreclr.dylib

The gating target is _CheckForUnsupportedMonoMobileRuntime in Microsoft.NET.TargetFrameworkInference.targets, covering android, ios, tvos and maccatalyst for TFM >= 11.0.

What to do at .NET 11 GA

Confirm Mono is actually gone for mobile, then:

• integration-test/android.Tests.ps1 — drop the mono cases and the _DisableCheckForUnsupportedMonoMobileRuntime injection
• integration-test/ios.Tests.ps1 — same
• test/Sentry.Android.AssemblyReader.Tests/Sentry.Android.AssemblyReader.Tests.csproj — the Mono AOT APK variants (_TestAPK 5-8) are already net10.0-android only; drop them entirely if Mono is gone, rather than widening them
• test/Sentry.Android.AssemblyReader.Tests/AndroidAssemblyReaderTests.cs — the NET11_0_OR_GREATER AOT skip
• Update CONTRIBUTING.md if the mobile runtime story is worth recording for next year's upgrade

If instead Mono survives into .NET 11 GA and only the _Disable... property goes away, the fix is smaller: delete that property from the two integration test scripts and keep the Mono cases.

Related

• Port upstream AssemblyStore reader changes: v4/CoreCLR format, _assembly_store symbol, index-entry sizing (next major) #5454 — Android assembly store v4. Note v4 is a .NET 11 Android workload change, not a CoreCLR one: a Mono net11 APK reports store version 0x80010004 (64-bit | aarch64 | v4), the same version as the CoreCLR build. Opting back to Mono is therefore not a symbolication workaround.