rlpenasp

This error isn’t new.
– https://github.com/Automattic/facebook-instant-articles-wp/issues/1030
– https://github.com/Automattic/facebook-instant-articles-wp/issues/989

I’ve made a workaround testing if de method exists.

$clone = null;
if(method_exists($node, ‘cloneNode’)){
$clone = $node->cloneNode(true);
if (isset($clone) && Type::is($clone, ‘DOMElement’) && $clone->hasAttribute(self::INSTANT_ARTICLES_PARSED_FLAG)) {
$clone->removeAttribute(self::INSTANT_ARTICLES_PARSED_FLAG);
}
}
return $clone;

I have the same problem here.