• MSDN Library

Visual C# Reference: Errors and Warnings

Compiler Error CS0012

Error Message

The definition for a referenced type was not found. This could occur if a required .DLL file is not included in the compilation. For more information, see Add Reference Dialog Box and /reference (Import Metadata) (C# Compiler Options).

The following sequence of compilations will result in CS0012:

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// cs0012a.cs
// compile with: /target:library
public class A {}

Then:

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// cs0012b.cs
// compile with: /target:library /reference:cs0012a.dll
public class B
{
   public static A f()
   {
      return new A();
   }
}

Then:

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// cs0012c.cs
// compile with: /reference:cs0012b.dll
class C
{
   public static void Main()
   {
      object o = B.f();   // CS0012
   }
}

You could resolve this CS0012 by compiling with /reference:cs0012b.dll;cs0012a.dll, or in Visual Studio by using the Add Reference Dialog Box to add a reference to cs0012a.dll in addition to cs0012b.dll.

我碰到这个错误是因为用到了一个类中的静态方法，而该类又实现了一个借口，而我又没有引用该接口。

解决办法很简单，在vs里面添加对接口的引用就可以了。就像上面所说的，根本问题在于类的连环引用。