The template on Joomla 3.8.0 does not work. I'm getting an error 404 when I try to load a site.

404
ERROR
Serialization of "SimpleXMLElement" is not allowed
GO BACK TO THE MAIN PAGE

Please help to solve the problem.
Thank you!

Dear German

To fix this issue, please go to modules\mod_sj_contact_ajax\mod_sj_contact_ajax.php find code:

$layout = $params->get('layout', 'default');
$cacheid = md5(serialize(array($layout, $module->id)));
$cacheparams = new stdClass;
$cacheparams->cachemode = 'id';
$cacheparams->class = 'ContactAjax';
$cacheparams->method = 'getList';
$cacheparams->methodparams = $params;
$cacheparams->modeparams = $cacheid;
$list = JModuleHelper::moduleCache($module, $params, $cacheparams);

=> edit to:

$layout = $params->get('layout', 'default');
$list = ContactAjax::getList($params);

Thanks & regards!