I was moving a WP from a host to another, and using the WordPress Importer while loading the XML of the export “Fatal error: Class ‘DOMDocument’ not found“.

We have two solutions

• Install the php-xml package on your server.
• Replace in file parsers.php in plugin wordpress-importer at class WXR_Parser_SimpleXML

Replace in file parsers.php in plugin wordpress-importer at Class WXR_Parser_SimpleXML

Change

$dom = new DOMDocument;
$old_value = null;
if ( function_exists( 'libxml_disable_entity_loader' ) ) {
$old_value = libxml_disable_entity_loader( true );
}
$success = $dom->loadXML( file_get_contents( $file ) );
if ( ! is_null( $old_value ) ) {
libxml_disable_entity_loader( $old_value );
}if ( ! $success || isset( $dom->doctype ) ) {
return new WP_Error( 'SimpleXML_parse_error', __( 'There was an error when reading this WXR file', 'wordpress-importer' ), libxml_get_errors() );
}$xml = simplexml_import_dom( $dom );
unset( $dom );

For:

$xml = simplexml_load_file($file);