Uncaught RuntimeException: Backtrack buffer overflow

It sounds like the plugin encountered an unusual log entry that it couldn’t parse correctly. This is probably a bug or at least a design oversight. Is there any chance that you could send me a copy of the log file for testing? My email is [email protected]

That varies a lot as it depends on the server configuration. Usually the location of the error log is set by the error_log configuration option in php.ini. See also the answers to this Stack Overflow question:
https://stackoverflow.com/questions/5127838/where-does-php-store-the-error-log-php5-apache-fastcgi-cpanel

If that doesn’t help or you can’t access the log, you might have to ask your hosting provider about it.