Starting with .NET 11 Preview 4, .NET MAUI applications on Android, iOS, and Mac Catalyst now run on CoreCLR by default—the same runtime that powers ASP.NET Core, Azure, and desktop apps. This shift unifies the runtime across mobile, server, and desktop, ending a 15-year reliance on Mono for mobile. While Mono remains in use for Blazor WebAssembly and older projects, the transition marks a major milestone. Below, we answer common questions about what changed, why, and what it means for developers.
What exactly changed in .NET MAUI with .NET 11?
In .NET 11 Preview 4, CoreCLR became the default runtime for Release and Debug builds of .NET MAUI apps on Android, iOS, Mac Catalyst, and tvOS. Previously, these platforms relied on Mono. This means your mobile app now runs on the same runtime that powers ASP.NET Core, Azure services, and Windows desktop applications. The change applies to all MAUI app types; for Blazor WebAssembly, Mono remains the runtime. If you encounter issues during the transition, you can opt back to Mono using a configuration flag.
Why did Mono power .NET mobile apps for so long?
Mono was created in 2001 by Miguel de Icaza to bring .NET to Linux. Over the years, it expanded far beyond its original scope. MonoTouch (2009) brought C# to iOS, MonoDroid to Android, and Xamarin later turned these into a full mobile platform. When Microsoft acquired Xamarin in 2016, Mono was the runtime underneath. Beyond Microsoft’s own ecosystem, Mono became the scripting backbone of Unity, Avalonia, Uno Platform, MonoGame, and Godot’s C# support. Mono proved that .NET could run anywhere, and its legacy extends across games, desktop, and even WebAssembly.
Why is CoreCLR better for mobile apps now?
Three main reasons drove this change: unification, performance, and tooling consistency. Until now, mobile apps ran on Mono while server and desktop apps ran on CoreCLR. This meant different JIT behaviors, garbage collector characteristics, and diagnostic tools. With CoreCLR across all platforms, your mobile app behaves identically to your backend—same runtime, same debugging, same profiling. This simplifies development, reduces unexpected behavior, and lets teams share optimizations. Additionally, CoreCLR has years of production tuning on millions of servers, bringing proven reliability to mobile devices.
How does this affect Unity, Avalonia, and other Mono-based projects?
While .NET MAUI moves to CoreCLR, many other projects still depend on Mono. Unity has already begun its own transition to CoreCLR, but the process is gradual. Avalonia and Uno Platform continue to use Mono on WebAssembly, though desktop builds often target CoreCLR. MonoGame and Godot remain on Mono for now. The key takeaway is that Mono isn’t being abandoned—it continues to serve platforms like Blazor WebAssembly and legacy mobile apps. Developers in those ecosystems can still use Mono without disruption, while MAUI developers gain access to CoreCLR’s broader tooling and performance.
Can I still use Mono if I have issues with CoreCLR on mobile?
Yes, during the transition period (.NET 11 previews and initial releases), you can opt back to Mono if you encounter issues. The option is a simple configuration toggle in your project file or build settings. Microsoft recommends trying CoreCLR first, as it offers better long-term support and alignment with the rest of .NET. However, if a critical library or plugin hasn’t been updated, reverting to Mono gives you a safety net. The community expects most compatibility issues to be resolved by .NET 11’s general availability.
Is Blazor WebAssembly also moving to CoreCLR?
No. Blazor WebAssembly is not affected by this change. It continues to use Mono as its runtime on WebAssembly, and that is not changing in .NET 11. CoreCLR does not currently support WebAssembly as a target, so Mono remains the right choice for browser-based .NET apps. This means if you build a MAUI app with Blazor hybrid, the mobile part runs on CoreCLR, but the Blazor WebAssembly portion still runs on Mono.
What should MAUI developers do to prepare for this change?
First, upgrade your project to .NET 11 Preview 4 or later. Then build and test your app on Android, iOS, and Mac Catalyst. Pay special attention to any third-party libraries or plugins that might have Mono-specific dependencies—check their documentation for CoreCLR compatibility. Update your diagnostic and profiling tooling to work with CoreCLR’s APIs. Finally, review the official Runtimes and compilation documentation for detailed guidance. The migration is designed to be smooth, but early testing ensures your app takes full advantage of CoreCLR’s performance and reliability.