C# Error CS8373 – The left-hand side of a ref assignment must be a ref variable.

C# Error

CS8373 – The left-hand side of a ref assignment must be a ref variable.

Reason for the Error & Solution

The left-hand side of a ref assignment must be a ref variable.

Example

The following sample generates CS8373:

// CS8373.cs (6,90)

public class C
{
    void M(int a, ref int b)
    {
        a = ref b;
    }
}

To correct this error

To assign the value of a ref variable, removing the ref keyword corrects this error:

public class C
{
    void M(int a, ref int b)
    {
        a = b;
    }
}