C# Error CS8151 – The return expression must be of type ‘{0}’ because this method returns by reference

C# Error

CS8151 – The return expression must be of type ‘{0}’ because this method returns by reference

Reason for the Error & Solution

The return expression must be of type because this method returns by reference

Example

The following sample generates CS8151:

// CS8151.cs (6,20)

class Program
{
    ref int M(ref long i)
    {
        return ref i;
    }
}

To correct this error

Ensuring that a ref return matches the type of the referenced variable regardless of any implicit conversions corrects this error:

class Program
{
    ref long M(ref long i)
    {
        return ref i;
    }
}