Java is better about this than most languages but they still break things sometimes. For example, in addition to the module system, Java 9 changed the implemen

Java is better about this than most languages but they still break things sometimes. For example, in addition to the module system, Java 9 changed the implementation of some of its XML rendering libraries and caused meaningful behavior changes. https://github.com/CodeFX-org/java-9-wtf https://github.com/CodeFX-org/java-9-wtf has a list of some of the stuff that broke. That said, 8 -> 9 was the only really painful transition in my experience. Since then the upgrades have been smoother.