System.IObserver'1<T0> is defined in an assembly that is not referenced. You must add a reference to assembly

Question

I have checked some code out of source control and am getting the following error when I try to build:

The type 'System.IObserver`1' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Observable, Version=1.0.0.204, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

So first port of call was to Google. Looks like I need the Rx Framework. So I downloaded the Reactive Extensions experimental release . I installed it completely, closed VS2010 SP1, and then went back in. Getting the same error.

What else could I need to do?

Answer 1

As the message says, your project needs to reference the System.Observable assembly. Simply installing the Rx framework doesn't add a reference to your project...

Answer 2

In Visual Studio

• Right-click the References folder of your project
• Click Add reference...
• In the Add Reference window, choose from Assemblies >> Extensions
• Click System.Observable from the list
• Click Add

Problem solved

Answer 3

您已经安装了所需的扩展，但您仍需要将其添加为项目中的参考。

Answer 4

Try downloading from NuGet. Right click, "Manage NuGet"... Search Online for "Rx_Exper.."

http://nuget.org/packages/Rx_Experimental-Silverlight/1.1.11111