Manifest Exception

************** Exception Text **************
System.Deployment.Application.InvalidDeploymentException: Exception reading manifest from file:///C:/Users/b012918/AppData/Roaming/Microsoft/AddIns/Project%20Count_Per%20Person.xlam: the manifest may not be valid or the file could not be opened. ---> System.Xml.XmlException: Data at the root level is invalid. Line 1, position 1.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)
   at System.Xml.XmlTextReaderImpl.ParseRootLevelWhitespace()
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.XmlTextReader.Read()
   at System.Deployment.Application.ManifestValidatingReader.XmlFilteredReader.Read()
   at System.Xml.XmlCharCheckingReader.Read()
   at System.Xml.XsdValidatingReader.Read()
   at System.Deployment.Application.ManifestReader.FromDocument(String localPath, ManifestType manifestType, Uri sourceUri)
   --- End of inner exception stack trace ---
   at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.GetManifests(TimeSpan timeout)
   at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.InstallAddIn()