Article ID: 2087, created on Aug 13, 2007, last review on May 8, 2014

  • Applies to:
  • Plesk for Windows


Domain is switched to load PHP as CGI extension. PHP pages cannot be browsed – authorization pages prompts or the following error is displayed:

CGI Error.
The specified CGI application misbehaved by not returning a complete set
of HTTP headers.

In case domain is switched to use PHP as ISAPI extension, the problem is gone.


Most likely the reason of the problem is that Plesk is installed to the path which contains spaces in its name -  e.g. C:\P S A. Provided that there are some folders on the disk which contain a part of name of this path IIS tries to access them at the first. E.g if there are C:\P S or C:\P folders, IIS tries to access them and fails because it doesn’t have appropriate permissions to these folders. 


Actually this is common IIS behavior. As workaround we can suggest the following:

1. Open disksecurity.xml

Begining from version 8.2 it is located in %plesk_dir%\etc\DiskSecurity
In all older versions it is located in folder %plesk_bin%.

2. Edit it and add next stings there:

<Entry AccounType="1" Account="Psacln" Path="C:\Program Files" AceFlags="ThisFolderAndSubfolders" AccessMask="FullAccess" EntryFlags="0x1"/>

<Entry AccounType="1" Account="Psacln" Path="C:\Program Files\Common" AceFlags="ThisFolderAndSubfolders" AccessMask="0x0080" EntryFlags="0x2"/> 

Note: Replace "C:\Program Files" with localized path. E.g. in case you have German OS , the path fill be "C:\Programme"

3. Once it’s done run the following command:

ApplySecurity --apply

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