Warning: Constant WPLANG already defined in /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-config.php on line 75

Fatal error: Uncaught Error: Call to undefined function create_function() in /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-content/plugins/appointment-booking-calendar/cpabc_appointments.php:1020
Stack trace:
#0 /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-settings.php(462): include_once()
#1 /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-config.php(93): require_once('/home/httpd/vho...')
#2 /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-load.php(50): require_once('/home/httpd/vho...')
#3 /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-login.php(12): require('/home/httpd/vho...')
#4 {main}
  thrown in /home/httpd/vhosts/donnerstern.ch/httpdocs/wp-content/plugins/appointment-booking-calendar/cpabc_appointments.php on line 1020