Problem at module.
Why we must fix Joomla core files?

hi dear drfoxg
of-course this is temporary way to fix problem
we should find problem and solve it Properly

The above solution worked for me.
Thanks

unfortunatelly this fix been working on Financial II template but not on Hexagon template
Should be a solution

Dear Sir,

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!

The quick fix by v.heydarpour on the previous page does work...
With newer Joomla Versions this fix is at:
/home/user/public_html/libraries/joomla/src/cache/controller/callbackController.php
in line 188