This message always displays on every page if open debug mode.
I searched it and found other php product said the problem can be solved by setting variables_order=EGPCS in php.ini. I tried but did not work. variables_order always be GPCS. The official php doc (http://php.net/manual/en/ini.core.php) says "In both the CGI and FastCGI SAPIs, $_SERVER is also populated by values from the environment; S is always equivalent to ES regardless of the placement of E elsewhere in this directive." It seems that GPCS is equal to EGPCS in my server