One example that comes to my mind: libraries that handle bytecode manipulation (e.g. javassist) may require to be updated because they give new and strange erro

One example that comes to my mind: libraries that handle bytecode manipulation (e.g. javassist) may require to be updated because they give new and strange error if they meet newly introduced bytecode. Since those libraries are often used by high level frameworks like Spring, this means that to move to a new Java version you have to update your framework. These most often means new API, new bugs, new regressions...