You need update Mighty Assistant component. If you cannot do that from back-end then you may download the latest version of Mighty Assistant component and install it over the current version via joomla installation manager. Here is the link:
I have the same problem, when syncronizing i get this problem:
# XML Parsing Error at 1:1. Error 4: Not well-formed (invalid token) # ERROR LOADING FEED DATA
And i cannot install any license, nor any component. I have downloaded the lastest version on this site, but I get this error.
What should I do?