getting InvalidClassException: org.hibernate.collection.AbstractPersistentCollection

[animesha10]

Hi,
  I am Using Activiti 5.1 and  while starting my Application i am getting java.io.InvalidClassException: org.hibernate.collection.AbstractPersistentCollection; local class incompatible: stream classdesc serialVersionUID = -5723701046347946317, local class serialVersionUID = 7602608801868099635

what could be the reason for this exception?

Thanks

[frederikherema1]

It seems you're using Hibernate alongside activiti and one of the (serialized) classes is using another version of Hibernate lib. Have you upgraded the lib recently?