Just had this error while trying to import a solution to Dynamics CRM 2013. On checking the log file I found that the error was with regard to a chart. It was easy to see which chart it was in relation to, so what was the issue?
Fortunately the log actually stated where the issues was. There were spurious characters in the XML, specifically “> or >, but it was being viewed as text. Not sure what happened there.
I opened up the Customisations.xml in the solution file, found the offending characters, deleted, saved and imported with success. 🙂