Compiler Error CS0834

 

Updated: July 20, 2015

For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

A lambda expression must have an expression body to be converted to an expression tree.

Lambdas that are translated to expression trees must be expression lambdas; statement lambdas and anonymous methods can only be converted to delegate types.

To correct this error

  1. Remove the statement from the lambda expression.

The following example generates CS0834:

// cs0834.cs  
using System;  
using System.Linq;  
using System.Linq.Expressions;  
  
public class C  
{  
    public static int Main()  
    {  
        Expression<Func<int, int>> e = x => { return x; }; // CS0834  
    }  
}  
  

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