Software⏱️ 2 min read📅 2026-06-03

How to Fix: Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

Learn how to fix: Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session.

Quick Answer: Try checking your system settings or restarting.

The NonUniqueObjectException in Hibernate occurs when you try to save an object that already exists in the database with the same identifier value. This is often due to a concurrency issue where two or more threads are trying to update the same object simultaneously.

🛑 Root Causes of the Error

  • Concurrency issues when multiple threads try to update the same object.

🚀 How to Resolve This Issue

Method 1: Lazy Loading

  1. Step 1: Use lazy loading by setting the 'fetch' property to 'join' in your Hibernate configuration file.

Method 2: Pessimistic Locking

  1. Step 1: Use pessimistic locking by setting the 'lock' property to 'pessimistic' in your Hibernate configuration file.

💡 Conclusion

By implementing one of these methods, you can resolve the NonUniqueObjectException and ensure that your application can handle concurrent updates to the same object.

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❓ Frequently Asked Questions