Fatal error: Uncaught Error: Call to undefined function is_blog_installed() in /var/www/vhosts/proton-mail.it/httpdocs/wp-includes/load.php:545 Stack trace: #0 /var/www/vhosts/proton-mail.it/httpdocs/wp-settings.php(140): wp_not_installed() #1 /var/www/vhosts/proton-mail.it/httpdocs/wp-config.php(89): require_once('/var/www/vhosts...') #2 /var/www/vhosts/proton-mail.it/httpdocs/wp-load.php(37): require_once('/var/www/vhosts...') #3 /var/www/vhosts/proton-mail.it/httpdocs/wp-blog-header.php(13): require_once('/var/www/vhosts...') #4 /var/www/vhosts/proton-mail.it/httpdocs/index.php(17): require('/var/www/vhosts...') #5 {main} thrown in /var/www/vhosts/proton-mail.it/httpdocs/wp-includes/load.php on line 545

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'wp_ob_end_flush_all' not found or invalid function name in /var/www/vhosts/proton-mail.it/httpdocs/wp-includes/class-wp-hook.php on line 286