PHP Fatal error: Call to undefined function chdir() I tried to copy my site to a new sever and since id did that, I get an HTTP-Fehler 500 (Internal Server Error): on certain pages. The log files are reporting:

PHP Fatal error:  Call to undefined function chdir() in /var/customers/webs/something/includes/bootstrap.inc on line 3384
PHP Fatal error:  Call to undefined function max() in /var/customers/webs/something/includes/lock.inc on line 106


I cleared all caches many times with:

drush cc all


and also flushed the cache tables directly with MySQL commands. I disabled APC. I don't think, that this is a problem with the server, because it serves well for other Durpal sites.

EDIT: Here are my php.ini and htaccess.
chdir() and max() are built in functions that always exists in PHP. They are in no plugin, just a core. Even in safe mode both should be defined. 

There is one way to disable them and make them non-existent from the script's point of view. disable_functions section in php.ini does the trick. Usually it is used for safety, like this:

disable_functions=exec,passthru,shell_exec,system,proc_open,popen,curl_exec,curl_multi_exec,parse_ini_file,show_source 


and whilst I can see some illusionary* safety in disabling chdir(), disabling max() must have been a mistake. Note that on some configurations you can alter ini settings in .htaccess and via ini_set() too.

*Illusionary due to the same reasons that made Safe Mode deprecated.