If you place a space at the end of the filename of a zip file, Jira assumes the file is formatted in xml causing this error:
/ * Error parsing export file. Your export file is invalid. This may be due to a CDATA bug in older versions of JIRA (//http://jira.atlassian.com/browse/JRA-4980//
). Exception is org.xml.sax.SAXParseException: Content is not allowed in prolog.