Hibernate: Null ID in Entry - Troubleshooting and Solutions

This error often occurs because an exception happened during the persistence process, causing the session to close or interrupt prematurely. Here's how to fix it:

1. Proper Exception Handling: Ensure your code correctly handles exceptions and avoids immediately flushing the session. Instead, attempt to rollback the transaction or retry the operation before committing again.

2. Hibernate Rollback: If you're using Hibernate, utilize the rollback() method within a catch block to ensure the session rolls back in case of an exception.

3. Try-with-Resources: Employ try-with-resources statements for guaranteed session closure even if exceptions arise.

4. Spring Framework: Leverage the @Transactional annotation in Spring to automatically rollback transactions upon exceptions.

In essence, you must handle exceptions properly during persistence. Rollback transactions or close the session gracefully when exceptions occur to prevent the 'null id in entry' error.