go to the extensions -> plugins and then find "Quick Icon - Joomla! Update Notification" and enable it.
try this : <?php $app = JFactory::getApplication(); $doc = JFactory::getDocument(); $this->language = $doc->language; $lng=explode('...
it's true! before the installation go to joomla_root\installation\sql there is only 3 folders (mysql - postgersql - sqlazure) and MSSQL is not included
i rolled back joomla version from 3.6.3 to 3.3.3 and the problem solved !