You must edit two files /libraries/src/Application/CMSApplication.php and libraries/joomla/session/handler/native.php
In libraries/src/Application/CMSApplication.php change code around line 166 and add if condition for whole code in method if (substr($_SERVER , 0 , 14) == "/administrator"){
public function checkSession()
{
if (substr($_SERVER['SCRIPT_NAME'] , 0 , 14) == "/administrator"){ // added condition
$db = \JFactory::getDbo();
$session = \JFactory::getSession();
$user = \JFactory::getUser();
// ... rest of code
}
}
In libraries/joomla/session/handler/native.php change code around line 229 add if condition for whole code in method like in previous fileprivate function doSessionStart()
{
if (substr($_SERVER['SCRIPT_NAME'] , 0 , 14) == "/administrator"){ // added condition
// Register our function as shutdown method, so we can manipulate it
register_shutdown_function(array($this, 'save'));
// ... rest of code
}
}
This works in Joomla 3.8.2