This error is caused from having open_basedir restrictions set to a value for your domain. You can determine this by viewing your phpinfo.php file at http://www.yourdomain.com/clientexec/newedge/diagnostics/phpinfo.php . The value present for open_basedir must be no value if you plan to use the Cpanel plugin.
You must have your host remove these restrictions from your domain in order for you to use the Cpanel plugin. Until your host makes this change for you, we recommend you disable the plugin under System setup=>servers=> Plugin Configuration to prevent errors.
If you have Root access to WHM, you may remove this by viewing the Tweak Security settings in WHM and remove it for the domain in question.
If you are using a control panel outside of Cpanel/WHM and receive this error, we recommend removing the /cpanel directory in /plugins/servers/.