Hi hamsterdancer and thanks for your hint.
Trying to setup the persistence with Postgres, I stumbled upon your same exception so I changed the file ${install.home}/db/ProcessInstanceInfo.hbm.xml from:
<property name="processInstanceByteArray" type="org.jbpm.persistence.processinstance.BlobUserType"
column="processInstanceByteArray" access="field" />
to:
<property name="processInstanceByteArray" type="org.hibernate.type.PrimitiveByteArrayBlobType"
column="processInstanceByteArray" access="field" length="2147483647" />
but trying to start a process I still have the same exception.
After that I changed also another ProcessInstanceInfo.hbm.xml in ${install.home}/runtime/jbpm-persistence-jpa-5.3.0.Final.jar but the exception is still there.
Any idea?