This problem occurs because you have specified an incorrect Apache group when installing Parallels Confixx. There are two ways to resolve this problem:
The first way:
Change the specified Apache group to the correct one in the confixx_main.conf file. The Apache group can be found in the Apache configuration file: httpd.conf (Group …).
Change the $apacheGroup and $gidapache in the confixx_main.conf file.
Run the Confixx update script (./admin/updates/update_3.x.pl). If you have not made an update of Parallels Confixx before you can make it now. You can update your Parallels Confixx to the latest version.
The second way is to change the “Group” in the httpd.conf Apache configuration file to the group, that was written in the confixx_main.conf ($apacheGroupvariable) file. The Apache group should be equal to the confixx_main.conf and httpd.conf.