Parent content types missing during site collection health check
When you run a site collection health check before upgrading to SharePoint 2013, you may find that the parent for a content type is missing.
To fix this issue, you will need to do one of the following actions:
Delete the orphaned content type.
Associate the orphaned content type with a parent content type.
For the steps to delete an orphaned content type or to associate a content type with a parent content type, see Create or customize a content type.