I got the error "To Large Session" after the trail to save a session. To resolve the issue it would be helpful to know at least the estimated size for the session so that one can set max_allowed_packet size or/and innodb_log_file_size to this estimated size.
It seems that the normal MySQL server is not able to handle log files >= 4 GB. This could be an advice for the upper bound. If innodb_log_file_size is set to 2048M (or probably bigger) this error is raised:
See also: http://dba.stackexchange.com/questions/33061/mysql-5-5-innodb-innodb-log-file-size-higher-than-4gb-combined
The dialog "too large session" now contains a recommendation for the two variables. The values are roughly 20% higher than the session might actually need. But since we are not sure how accurate our calculations on the session size are, we require these extra 20%.
I attached a picture of the dialog as it looks now. If it should be changed in any way we should discuss it here.