Hi Ville Itämaa,
I havent tried configuring the JBPM with MySQL, but are you using the correct hibernate dialect?
From the guide here http://docs.jboss.org/jbpm/v5.3/userguide/ch.installer.html#d0e597
they seem to use <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/> instead of <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLInnoDBDialect"/>
I am not sure if it was the cause of your problem.
Regards,
Thomas Setiabudi