I had a lot of trouble changing from 5.2 to 5.3. First of all my old data didn't load anymore. I had to delete my old ksession (since I'm on a development environment I didn't need to care about it) so the new version would start. I also had a lot of problems fixing my initialization process since the same initialization that was working on 5.2 didn't work on 5.3 (my ksession was getting corrupted a lot). There was also some changes needed due to name changes on classes or interfaces on drools 5.4 but that was easy and quick to fix. My advice is to take care when upgrading and obviously not doing it on a production environment.
Thanks Bira for share your experiences. I don't know if the team mention this problem. But, if they make no compatible each release, is problematic update to a new version. If you can migrate please share how do you make this work.
As for my eperience upgrading, this post summarizes it. https://community.jboss.org/thread/200546
Another thing... when using the mapping on JPBMorm.xml I had to change date fields from type DATE to TIMESTAMP. First, because DATE makes you get only the ymd part of a date... which may not be very useful. Second, because doing so also fixed some issues (I don't really remember what the problem was anymore... but I would advise using TIMESTAMP instead to make sure)
Please notice that I didn't really migrate any data though... I just upgraded the jbpm version and deleted the old data from the database.
Thanks Bira for sharing. I assume that the question posted by Asaf: "I upgrade my current processes will be unreadbale or is this backwards compatible?" Is YES. I guess something of Jbpm team give us an official answer and said if is posible to migrate sessions.
Thanks a lot Bira and gardellajp. So it seems there is no way to migrate data from 5.2 to 5.3 from their experiences.
This seems like a pretty big decision, I'm surprised it wasn't in bold red letters in the release notes. It would be great if someone from the JBPM team can confirm this.
I am also in a similar situation where I have upgrade from JBPM 5.2 to JBPM 5.4 version. My production environment has around 10100 In-Progress process Instances which also need to work properly after the JBPM5.4 version upgrade.
Is there any best practice which I am unaware of for the JBPM version upgrade ?