sebastian haas, thanks for the bug report and the detailed analysis provided. TBH, I was not aware that annotations are cached this way. There seems indeed to be a AnnotationData cache which can get invalidated as per comments

// annotation data that might get invalidated when JVM TI RedefineClasses() is called

I guess a simple workaround would be to use the Hibernate Validator internal proxy annotation (AnnotationProxy) for all cases. ATM these internal proxies are only used for constraints configured via XML.

If you could provide a test case that would still be awesome. It would be nice to first reproduce the problem. This way we can also make sure that the bug is fixed.