in xamp/php/php.ini search and modify php.ini file, search ;extension=php_xsl.dll line, remove ; at the line start and save php.ini file. Then open xampp manager, stop Apache services and restart again.
This is because the XSL extension is not enabled. To enable the XSL extension go to the location where the MAMP (or XAMPP) is installed. Then go to php/php.ini. Un-comment the line extension=php_xsl.dll and restart the server.