Compiler Error CS0743

Expected contextual keyword 'on'

The pattern for a join clause is join...in...on...equals, as shown in this example:

var query = from x in array1
            join y in array2 on x equals y
            select x;

To correct this error

• Add the on keyword to the join clause.

Example

The following code generates CS0743:

// cs0743.cs
using System;
using System.Linq;

public class C
{
    public static int Main()
    {
        int[] array1 = { 1, 2, 3 ,4, 5, 6,};
        int[] array2 = { 5, 6, 7, 8, 9 };
        var c = from x in array1
                join y in array2 x equals y // CS0743
                select x;
        return 1;
    }
}

See Also

Concepts

LINQ Query Expressions (C# Programming Guide)

Reference

join clause (C# Reference)