Fatal error: Uncaught Error: Call to undefined function _is_utf8_charset() in /home/.sites/21/site1018/web/wp-includes/functions.php:7509
Stack trace:
#0 /home/.sites/21/site1018/web/wp-includes/functions.php(7525): is_utf8_charset('utf-8')
#1 /home/.sites/21/site1018/web/wp-includes/functions.php(4313): _canonical_charset('utf-8')
#2 /home/.sites/21/site1018/web/wp-includes/functions.php(3804): _wp_die_process_input('Briefly unavail...', 'Maintenance', Array)
#3 /home/.sites/21/site1018/web/wp-includes/functions.php(3787): _default_wp_die_handler('Briefly unavail...', 'Maintenance', Array)
#4 /home/.sites/21/site1018/web/wp-includes/load.php(388): wp_die('Briefly unavail...', 'Maintenance', Array)
#5 /home/.sites/21/site1018/web/wp-settings.php(76): wp_maintenance()
#6 /home/.sites/21/site1018/web/wp-config.php(101): require_once('/home/.sites/21...')
#7 /home/.sites/21/site1018/web/wp-load.php(50): require_once('/home/.sites/21...')
#8 /home/.sites/21/site1018/web/wp-blog-header.php(13): require_once('/home/.sites/21...')
#9 /home/.sites/21/site1018/web/index.php(17): require('/home/.sites/21...')
#10 {main}
  thrown in /home/.sites/21/site1018/web/wp-includes/functions.php on line 7509