The problem with Java migrations is sometimes people (ab)use the behavior of a specific library in that specific version, and when you change the runtime, every

The problem with Java migrations is sometimes people (ab)use the behavior of a specific library in that specific version, and when you change the runtime, everything comes crashing down (visibly or invisibly). I have seen quite a few Java applications which fails at unrelated points, and every time I have been told that the thing only runs with "jre-old.very.specific.version-and.point.release". Otherwise you're out of luck.