$doc = new DOMDocument();$doc->load('test.xml');$user = $doc->getElementsByTagName('uname');$new = $doc->createElement('uname', 'not a test');$old = $user->item(0);$test = $doc->replaceChild($new, $old); <--- LINE 18echo $doc->saveXML();Fatal error: Uncaught exception 'DOMException' with message 'Not Found Error' in C:\AppServ\www\EMB\test.php:18 Stack trace: #0 C:\AppServ\www\EMB\test.php(18): DOMNode->replaceChild(Object(DOMElement), Object(DOMElement)) #1 {main} thrown in C:\AppServ\www\EMB\test.php on line 18