Problem with JavaRosa Parsing Form on form upload

after successful login to my ODK aggregate site. I cant upload any .xml forms due to this error:
Error: Problem with JavaRosa Parsing Form: org.opendatakit.aggregate.exception.ODKIncompleteSubmissionData: org.javarosa.xform.parse.XFormParseException: XML Syntax Error at Line: 11, Column: 12!

You are probably uploading an XLSForm. Aggregate needs an XForm. You can convert it at