Hibernate 6.6 Optimistic Lock Exception in Spring Boot Tests After Upgrade

Problem Statement

After upgrading to Spring Boot 3.4.0 (which includes Hibernate 6.6.x), integration tests using @SpringBootTest suddenly fail with JPA save operations. Tests that previously worked now throw:

org.springframework.orm.ObjectOptimisticLockingFailureException: Row was updated or deleted by another transaction
Caused by: org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction

This occurs when saving entities where the ID is manually set despite being marked as @GeneratedValue, such as:

// Test code triggering failure
var musterEntity = MusterMetadatenGenerator.createDefaultMuster();
musterMetadatenRepository.saveAndFlush(musterEntity); // Exception here

The entity's ID is defined with auto-generation:

@MappedSuperclass
public class BaseEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(updatable = false, nullable = false)
    protected UUID id; // Auto-generated but manually set in test
}

Cause

Hibernate 6.6 (included in Spring Boot 3.4.0) introduced critical behavior changes for ID handling:

1. Stricter Optimistic Lock Enforcement: When saving entities with manually set IDs that are also annotated with @GeneratedValue, Hibernate now treats them as detached (pre-existing) entities.
2. New Merge Behavior: If the database contains no matching row for the provided ID, Hibernate throws StaleObjectStateException (previously an insert was attempted).
3. Root Issue: Manually setting IDs for entities with @GeneratedValue contradicts Hibernate's entity lifecycle rules. This was tolerated in Hibernate 6.5.x but is now explicitly blocked.

Key Change

GenerationType.AUTO no longer implies allowAssignedIdentifiers=true. Manually assigned IDs with @GeneratedValue trigger the new strict handling.

Solution

Remove manual ID assignment in entity creation logic. Let Hibernate generate IDs as configured.

Step-by-Step Fix

1. Modify Entity Creation Helper: Ensure ID isn't manually set

   static <E extends BaseEntity> E createDefaultValues(
         @NotNull final E source,
         @NotNull final LocalDate datumAb,
         @NotNull final LocalDate datumBis
   ) {
       final Instant now = Instant.now();
       // Remove manual ID assignment
       // source.setId(UUID.randomUUID()); // Delete this line
       
       source.setDatumAb(datumAb);
       source.setDatumBis(datumBis);
       source.setBearbeitetAm(now);
       source.setErstelltAm(now);
       return source;
   }

2. Verify Entity State: Ensure entities have null IDs before saving:

   @Test
   void retrieveAllFahrzeugbewegungenByMuster() {
       var musterEntity = MusterMetadatenGenerator.createDefaultMuster();
       
       // ID should be null before save 
       assertThat(musterEntity.getId()).isNull(); 
       
       musterMetadatenRepository.saveAndFlush(musterEntity);
       // ...
   }

Why This Works

• Aligns with @GeneratedValue contract: The DB/provider generates the ID
• New entities start with id=null, signaling Hibernate to treat them as transient
• Fixes the mismatch where Hibernate 6.6 expects generated IDs to be unassigned

Background: Hibernate 6.6 Changes

The core behavior change is in DefaultMergeEventListener (added in HHH-1661). Key differences:

<CodeGroup> <CodeGroupItem title="Hibernate 6.5 (Spring Boot < 3.4.0)">

if (result == null) {
   // Would attempt insert even with manual ID
}

</CodeGroupItem> <CodeGroupItem title="Hibernate 6.6 (Spring Boot ≥ 3.4.0" active>

if (result == null) {
   LOG.trace("Detached instance not found in database");
   if (knownTransient == Boolean.FALSE) {
      // New behavior: Throw if entity has
      // generated @Id but no DB record exists
      throw new StaleObjectStateException(entityName, id);
   }
}

</CodeGroupItem> </CodeGroup>

Best Practice

Always treat @GeneratedValue fields as read-only for new entities. Never assign explicit IDs unless using @Id without generation.

When Assigning IDs is Intentional

If your design requires manual ID assignment:

1. Replace @GeneratedValue with custom ID handling
2. Use @Id without generation:

   @Id
   @Column(updatable = false, nullable = false)
   protected UUID id; // No @GeneratedValue

3. Explicitly manage ID uniqueness in application logic

Additional Resources

• Hibernate 6.6 Migration Guide
• HHH-1661: Entity merge behavior refinement
• Spring Boot issue tracking Hibernate 6.6 upgrade: #43100