hibernate/hibernate-orm · error · HibernateException

Immutable collection was modified: ${collectionInfo}

Error message

Immutable collection was modified: ${collectionInfo}

What it means

Error "Immutable collection was modified: ${collectionInfo}" thrown in hibernate/hibernate-orm.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/engine/spi/CollectionEntry.java:179

			|| loadedPersister.getElementType().isMutable();
	}

	private boolean isModifiable() {
		return !readOnly
			&& loadedPersister != null
			&& loadedPersister.isMutable();
	}

	public void preFlush(PersistentCollection<?> collection) {
		if ( loadedKey == null ) {
			loadedKey = collection.getKey();
		}

		final var loadedPersister = this.loadedPersister;
		if ( collection.isDirty()
				&& loadedPersister != null
				&& !isModifiable() ) {
			throw new HibernateException( "Immutable collection was modified: " +
					collectionInfoString( loadedPersister.getRole(), getLoadedKey() ) );
		}

		dirty( collection );

		if ( CORE_LOGGER.isTraceEnabled()
				&& loadedPersister != null
				&& collection.isDirty() ) {
			CORE_LOGGER.collectionDirty(
					collectionInfoString( loadedPersister.getRole(), getLoadedKey() ) );
		}
	}

	public void postInitialize(PersistentCollection<?> collection, SharedSessionContractImplementor session) {
		final var loadedPersister = this.loadedPersister;
		snapshot = loadedPersister != null && isModifiable() ? collection.getSnapshot( loadedPersister ) : null;
		collection.setSnapshot( loadedKey, role, snapshot );
		if ( loadedPersister != null

View on GitHub (pinned to fad1729dce)

Solutions

1. Do not modify a collection mapped as immutable; replace it or make the mapping mutable
2. Remove the immutability restriction from the collection mapping

When it happens

Trigger: Thrown at hibernate-core/src/main/java/org/hibernate/engine/spi/CollectionEntry.java:179 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/3bf3b2d485dc5547. Report an issue: GitHub.