The following error message is returned by Infopath when publishing a form to SharePoint 2010:
“This problem occurs because InfoPath makes a call to determine the version of SharePoint Server that is being run by the server. This call is performed as part of the publishing process, and the call is made to the root site collection. When no root site collection exists, the call cannot to determine the version of SharePoint Server that is being run by the server. Therefore, the publishing process fails.”
To resolve this problem, create a root site collection for the SharePoint 2010 site.