hibernate/hibernate-orm · error · NullPointerException

null merge entities are not supported by

Error message

null merge entities are not supported by 

What it means

Error "null merge entities are not supported by " thrown in hibernate/hibernate-orm.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/event/spi/MergeContext.java:323

	 * Returns an unmodifiable Set view of managed entities contained in this MergeContext.
	 * @return an unmodifiable Set view of managed entities contained in this MergeContext
	 *
	 * @see Collections#unmodifiableSet(Set)
	 */
	public @Nonnull Collection<Object> values() {
		return Collections.unmodifiableSet( managedToMergeEntityXref.keySet() );
	}

	/**
	 * Returns true if the listener is performing the merge operation on the specified merge entity.
	 * @param mergeEntity the merge entity; must be non-null
	 * @return true if the listener is performing the merge operation on the specified merge entity;
	 * false, if there is no mapping for mergeEntity.
	 * @throws NullPointerException if mergeEntity is null
	 */
	public boolean isOperatedOn(@Nonnull Object mergeEntity) {
		if ( mergeEntity == null ) {
			throw new NullPointerException( "null merge entities are not supported by " + getClass().getName() );
		}
		final Boolean isOperatedOn = mergeEntityToOperatedOnFlagMap.get( mergeEntity );
		return isOperatedOn != null && isOperatedOn;
	}

	/**
	 * Set flag to indicate if the listener is performing the merge operation on the specified merge entity.
	 * @param mergeEntity must be non-null and this MergeContext must contain a cross-reference for mergeEntity
	 *                       to a managed entity
	 * @throws NullPointerException if mergeEntity is null
	 * @throws IllegalStateException if this MergeContext does not contain a a cross-reference for mergeEntity
	 */
	public void setOperatedOn(@Nonnull Object mergeEntity, boolean isOperatedOn) {
		if ( mergeEntity == null ) {
			throw new NullPointerException( "null entities are not supported by " + getClass().getName() );
		}
		if ( ! mergeEntityToOperatedOnFlagMap.containsKey( mergeEntity ) ||
			! mergeToManagedEntityXref.containsKey( mergeEntity ) ) {

View on GitHub (pinned to fad1729dce)

Solutions

1. Ensure the merge entity key is non-null before interacting with the merge context.

When it happens

Trigger: Thrown when a null key or value is put into the merge-to-managed mapping of a MergeContext.

Common situations: Typical situations: merging a graph containing null elements; cascade-merge reaching a null association or collection element.

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/04d9978bcffa0e41. Report an issue: GitHub.