Hi Sarthak, It's mostly inevitable that you'll face breaking changes during the migration from such old version, and the impact will depend heavily on which features you're using. Some changes will be more significant than others.
Regarding versioning: 8.x and 9.x are effectively dead versions at this point. You should focus on 10.x as the only actively developed line. 8.x and 9.x were largely experimental releases and are now unmaintainable. - Alex On Sun, Feb 15, 2026 at 8:07 PM, Sarthak Barik <[email protected]> wrote: > Hi all, > > I need to migrate a legacy application from Drools 5.6.0.Final > <http://5.6.0.final/> to the latest stable Drools version. > > Current Setup: > - Drools Version: 5.6.0.Final <http://5.6.0.final/> (circa 2013) > - Rule Format: Traditional DRL files (DRL6 syntax) > - API: Using deprecated Knowledge API (KnowledgeBase, KnowledgeBuilder, > StatelessKnowledgeSession) > > Questions: > 1. What's the latest stable production-ready version of Drools/Apache KIE? > - Is 10.1.0 (July 2025) considered stable for production use? > - Or should I target 9.44.0.Final <http://9.44.0.final/> or 8.44.2. > Final <http://8.44.2.final/> instead? > - I'm learning Drools and noticed the versioning changed - 9.x uses > ".Final" suffix > but 10.x doesn't. Is this due to the Apache transition? How do I > identify stable > releases in the new versioning scheme? > > 2. DRL Backward Compatibility: > - Will DRL files written for Drools 5.6.0.Final <http://5.6.0.final/> > work unchanged in the latest version? > - Are there breaking syntax changes between 5.x and 10.x? > - Is there migration documentation or guidance for upgrading DRL > files? > - Can I use drools-engine-classic for backward compatibility while > migrating the API layer? > > 3. Documentation: > - The documentation at https://docs.drools.org/ only shows up to > 8.x. Is there > updated documentation for 9.x and 10.x? > - Where can I find Apache KIE Drools documentation for the latest > versions? > > My goal: Upgrade to the latest Java (21+) and Drools version without > rewriting > business rules, by updating only the API integration layer. > > Any guidance, documentation links, or real-world migration experiences > would be greatly > appreciated! > > -- > Regards > Sarthak Kumar Barik >
