Exporting XMLs for Dolby Vision
It is important to make sure that you have exported the proper type of XML from your projects timeline. It is quite possible that the wrong XML format was chosen from the drop down menu during export.
Solutions to consider
In the above error received, The XML file you are verifying is not a Dolby Vision metadata xml, but a Final Cut Pro, or fcp xml.
Re-export the xml, and choose Dolby Vision