Warning: require(functions.php): Failed to open stream: No such file or directory in /mnt/web022/c1/45/511528445/htdocs/index.php on line 23

Fatal error: Uncaught Error: Failed opening required 'functions.php' (include_path='./library:./application/models/:.:/opt/RZphp81/includes') in /mnt/web022/c1/45/511528445/htdocs/index.php:23
Stack trace:
#0 {main}
  thrown in /mnt/web022/c1/45/511528445/htdocs/index.php on line 23