David Hansmann I suspect the collection loading is done this way because some batching is enabled. So it tries to load several elements at once. But it should affect them to the right collection after that so you shouldn't end up with incorrect objects in your collections. Look for hibernate.default_batch_fetch_size.

Do you really see invalid elements in your collection or was it a supposition?

As for the cache exception, are you using @Cache(usage = CacheConcurrencyStrategy.NONE) on this particular entity by any chance? I can reproduce the exception by using this particular option.

Note that using this option basically disables the cache.