PHP Error after server upgraded

After the server was upgraded to PHP 5.5 I get the following errors. I see people have posted this same issue and a rep responds they were helped but never posts the fix. Please post the fix.

Warning: require(/home/domainname/public_html/admin/config/ProjectConfig.5.5.php): failed to open stream: No such file or directory in /home/howellpd/public_html/admin/config/ProjectConfig.php on line 1

Fatal error: require(): Failed opening required '/home/howellpd/public_html/admin/config/ProjectConfig.5.5.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/domainname/public_html/admin/config/ProjectConfig.php on line 1