This error typically appears when the panel can't establish a connection to the MySQL server. First, ensure MySQL is running with systemctl status mysql. If it’s stopped, restart it. Check your /home/xtreamcodes/iptv_panel/admin/config.php to verify DB credentials (host, username, password). Common issues include wrong password, corrupt my.cnf file, or full disk space. You can also test the connection manually using mysql -u root -p to ensure credentials are valid. If DB is corrupted, restore from backup or check for .err logs in /var/log/mysql.