convert.cs

        public override T GetFieldValue<T>(int ordinal)
        {
            try
            {
                return base.GetFieldValue<T>(ordinal);
            }
            catch (InvalidCastException e)
            {
                return ConvertWithReflection<T>(ordinal, e);
            }
        }

        public override async Task<T> GetFieldValueAsync<T>(int ordinal, CancellationToken cancellationToken)
        {
            try
            {
	        return await base.GetFieldValueAsync<T>(ordinal, cancellationToken).ConfigureAwait(false);
            }
            catch (InvalidCastException e)
            {
                return ConvertWithReflection<T>(ordinal, e);
            }
        }

        private T ConvertWithReflection<T>(int ordinal, InvalidCastException e)
        {
            try
            {
                // try casting using reflection
                var dataParam = Expression.Parameter(typeof(string), "data");
                var body = Expression.Block(Expression.Convert(dataParam, typeof(T)));
                var run = Expression.Lambda(body, dataParam).Compile();
                return (T) run.DynamicInvoke(GetReader().GetValue(ordinal));
            }
            catch (Exception)
            {
                // throw original InvalidCastException
                throw e;
            }
        }