The following Sync status error is returned does anyone know how to resolve?

An error has occured during processing ‘myemail@me.com' mailbox. System.InvalidOperationException: There is an error in XML document (6, 1). ---> System.Xml.XmlException: Data at the root level is invalid. Line 6, position 1. at System.Xml.XmlTextReaderImpl.Throw(Exception e) at System.Xml.XmlTextReaderImpl.ParseRootLevelWhitespace() at System.Xml.XmlTextReaderImpl.ParseDocumentContent() at System.Xml.XmlReader.ReadEndElement() at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderMasterCategoryList.Read6_MasterCategoryList(Boolean isNullable, Boolean checkType) at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderMasterCategoryList.Read7_categories() --- End of inner exception stack trace --- at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events) at System.Xml.Serialization.XmlSerializer.Deserialize(TextReader textReader) at PX.Data.Update.WebServices.PXExchangeServer.EnsureCategory(String mailbox, String name, CategoryColor color, CategoryKeyboardShortcut shortcut) at PX.Objects.CS.Email.ExchangeBaseLogicSyncCommand`3.EnsureEnvironmentConfigureduT](IEnumerable`1 mailboxes, PXSyncFolderSpecificationt] folders)