PHP Manual
DOMNode
Forbids serialization unless serialization methods are implemented in a subclass

DOMNode::__sleep

(PHP 8 >= 8.1.25)

DOMNode::__sleep — Forbids serialization unless serialization methods are implemented in a subclass

public DOMNode::__sleep(): array

Forbids serialization unless serialization methods are implemented in a subclass.

This function has no parameters.

The method always throws an exception.

Throws an Error exception when called.