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Debugging ReactiveUI

Every ReactiveUI package on NuGet ships with SourceLink metadata embedded in the assembly's PDB (<DebugType>embedded</DebugType> + Microsoft.SourceLink.GitHub, configured once in src/Directory.Build.props). That means you can step from your own code straight into the framework source on GitHub at the exact commit your installed version was built from — no matching local clone, no symbol-server hunting.

Visual Studio (2022 and newer)

Two debugger settings unlock SourceLink stepping. Both live under Tools → Options → Debugging:

  • 1. General page - Enable Just My Code — uncheck. With Just My Code on, the debugger never asks the SourceLink resolver for framework frames; turning it off lets the resolver fetch the matching ReactiveUI source on demand. - Enable Source Link support — check. This is the master switch that wires Microsoft.VisualStudio.Debugger.SourceLink into the symbol load path. - (Recommended) Enable source server support + Suppress JIT optimization on module load (Managed only) — gives you readable locals when stepping into release-built framework code.
  • 2. Symbols page - Make sure Microsoft Symbol Servers (or another server hosting the ReactiveUI PDBs — typically not needed since embedded ships the PDB inside the .dll itself) is enabled. With embedded PDBs, no extra server entry is required.

Set a breakpoint, hit it, then Step Into (F11) any ReactiveUI call (e.g. this.WhenAnyValue(...)). Visual Studio prompts once with *"Source Link will download https://raw.githubusercontent.com/reactiveui/... — OK?"*; accept and you'll land in WhenAnyMixin.cs at the exact commit your NuGet package was published from.

Rider / VS Code (C# Dev Kit)

Rider honors SourceLink out of the box — make sure Settings → Build, Execution, Deployment → Debugger → Enable external source debug is on, and disable Just My Code under the same screen.

In VS Code with the C# Dev Kit, set in launch.json:

{
    "justMyCode": false,
    "suppressJITOptimizations": true,
    "symbolOptions": {
        "searchMicrosoftSymbolServer": true
    }
}

Quick demo

Troubleshooting

  • Step Into still skips framework frames. Confirm Just My Code is off and that the package version on disk matches a published release tag (the SourceLink URL embeds the commit SHA — local builds without a release commit can't be resolved).
  • The remote endpoint could not be reached. Your network blocks raw.githubusercontent.com. Either whitelist that host or run with the source already on disk and point Visual Studio at it via Debug → Options → Symbols → Specify excluded modules.
  • Mobile heads (iOS / Android via .NET MAUI). The platform debuggers honor SourceLink for managed code today, but native interop frames stay opaque. For pure-managed ReactiveUI calls the experience matches WPF / WinForms.