Warning: require(./source/class/class_core.php): failed to open stream: No such file or directory in D:\localuser\ftp6107825\Web\forum\forum.php on line 15

Fatal error: require(): Failed opening required './source/class/class_core.php' (include_path='.;C:\php\pear') in D:\localuser\ftp6107825\Web\forum\forum.php on line 15