ResolutionThis article describes versions of PHP that can be used in Plesk and the recommended configuration of php.ini files.
There are two versions of PHP included with and supported by Plesk: PHP4 and PHP5. PHP can work in two modes: as CGI or as ISAPI. Both versions of PHP use php.ini files that are different depending on the version of PHP.
The default location of php.ini for PHP4 is the Windows base directory %systemroot%.
The default location of php.ini for PHP5 is the PleskPHP5 base directory %plesk_dir%Additional\PleskPHP5.
A custom php.ini with PHP4 in CGI mode can be used. In order to apply that, the php.ini file needs to be placed in the /httpdocs folder.
However, there is no such option with PHP4 in ISAPI mode which always uses the default php.ini of PHP4. Also, there is no option in PHP5 in either mode, where the default php.ini of PHP5 is used.
The default location of the php.ini file in PHP5 is defined by the following value in the registry:
Additional InformationConsult this article for more information on the differences between the ISAPI and CGI modes: