class Base
{
    public virtual void Foo(int[] arr) {}
}

class Derived : Base
{
    public override void Foo(params int[] arr)
    {
        base.Foo(arr);
    }
    
    void Bar()
    {
        Foo(1); // error CS1503: Argument '1': cannot convert from 'int' to 'int[]'
    }
}