Tag: System.Core

Reactive Framework conflict (SOLVED)

The type ‘System.IObservable exists in both ‘c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\mscorlib.dll’ and ‘c:\Program Files (x86)\Microsoft Reactive Extensions\Redist\DesktopV2\System.Observable.dll’ (SOLVED)

During an upgrade of a C# WPF application that was using Reactive Extensions, I ran into this compile error:

The type ‘System.IObservable exists in both ‘c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\mscorlib.dll’ and ‘c:\Program Files (x86)\Microsoft Reactive Extensions\Redist\DesktopV2\System.Observable.dll’

This is roughly the same kind of Defined in Multiple Assemblies problem as I faced before. (Solution provided.)

In this case, the System.Observable.dll was pinned to the 3.5 release of the Reactive Extensions.

The solution was to:

  1. Download the .NET 4.0 version of Reactive Extensions (Rx_Net4.msi).
  2. Install it.
  3. Remove System.Observable from the project.
  4. Re-add the System.Observable to the project, being super careful to select the latest version