Transaction marked as rollback only: How do I find the cause

I finally understood the problem:

methodA() {
    methodB()
}

@Transactional(noRollbackFor = Exception.class)
methodB() {
    ...
    try {
        methodC()
    } catch (...) {...}
    log("OK");
}

@Transactional
methodC() {
    throw new ...();
}

What happens is that even though the methodB has the right annotation, the methodC does not. When the exception is thrown, the second @Transactional marks the first transaction as Rollback only anyway.

When you mark your method as @Transactional, occurrence of any exception inside your method will mark the surrounding TX as roll-back only (even if you catch them). You can use other attributes of @Transactional annotation to prevent it of rolling back like:

@Transactional(rollbackFor=MyException.class, noRollbackFor=MyException2.class)