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Compiler Error CS0834

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

  • 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