Change the line:
$go_info["server"]["apache2_php"] = 'both';
$go_info["server"]["apache2_php"] = 'addtype';
in the file /home/admispconfig/ispconfig/lib/config.inc.php
This is the correct and only solution!
Some readers said that this error is ininfluent, but for my particular case this is very tedious. Infact when I attempt to upload some data through a form (text area) if the content is too large the server answers (it is not possible to display the page) and the upload stops without success.
This is not related to the above error. Just set the memory limit and limit for max. post data size in your php,ini to a higher value.