If you check the message after ResponseText, it says:
ResponseText: Fatal error: Maximum execution time of 30 seconds
exceeded in C:\xampp\htdocs\drupal7.50\includes\database\database.inc
on line 2204
Which means the process has taken more than default execution time set for PHP which is 30 seconds. You can increase the execution time by editing php.ini file located at "C:\xampp\php\php.ini" and setting value of max_execution_time
variable to more than 30. And then restart Apache.
The above change will be applicable to all site running from your local. To make it specific to particular site you can use one of the following method:
By editing settings.php located at "sites/default/settings.php" and adding following line:
ini_set('max_execution_time', 120);
Or you can also modify .htaccess file located in your Drupal root and add following line:
php_value max_execution_time 120