Warning: session_start(): Session cannot be started after headers have already been sent in /customers/a/b/8/printsign.dk/httpd.www/lightsign/include/config.php on line 3

Fatal error: Uncaught ArgumentCountError: mysqli_set_charset() expects exactly 2 arguments, 1 given in /customers/a/b/8/printsign.dk/httpd.www/lightsign/include/config.php:18
Stack trace:
#0 /customers/a/b/8/printsign.dk/httpd.www/lightsign/include/config.php(18): mysqli_set_charset('utf8')
#1 /customers/a/b/8/printsign.dk/httpd.www/lightsign/login.php(2): include('/customers/a/b/...')
#2 {main}
  thrown in /customers/a/b/8/printsign.dk/httpd.www/lightsign/include/config.php on line 18