hibernate/hibernate-orm · error · HibernateException

Unable to instantiate specified auto SessionEventListener: {

Error message

Unable to instantiate specified auto SessionEventListener: {}

What it means

The hibernate.session.events.auto setting names a SessionEventListener implementation class that Hibernate instantiates once per new Session. SessionFactoryOptionsBuilder.instantiateAutoSessionEventListener calls its public no-arg constructor; any failure throws HibernateException naming the class with the cause attached. Instantiation happens when the baseline listener array is built, i.e. at SessionFactory creation or first session use.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/boot/internal/SessionFactoryOptionsBuilder.java:1210

	public SessionEventListener[] buildSessionEventListeners() {
		if ( StatisticalLoggingSessionEventListener.isLoggingEnabled() ) {
			return autoSessionEventListener == null
					? new SessionEventListener[] { statsListener() }
					: new SessionEventListener[] { statsListener(), instantiateAutoSessionEventListener() };
		}
		else {
			return autoSessionEventListener == null
					? EMPTY_SESSION_EVENT_LISTENERS
					: new SessionEventListener[] { instantiateAutoSessionEventListener() };
		}
	}

	private SessionEventListener instantiateAutoSessionEventListener() {
		try {
			return autoSessionEventListener.getConstructor().newInstance();
		}
		catch (Exception e) {
			throw new HibernateException(
					"Unable to instantiate specified auto SessionEventListener: " + autoSessionEventListener.getName(),
					e
			);
		}
	}

	private static SessionEventListener statsListener() {
		return new StatisticalLoggingSessionEventListener();
	}

	@Override
	public boolean isIdentifierRollbackEnabled() {
		return identifierRollbackEnabled;
	}

	@Override
	public boolean isCheckNullability() {
		return checkNullability;

View on GitHub (pinned to fad1729dce)

Solutions

1. Give the listener class a public no-argument constructor
2. Inspect the nested cause to see whether construction threw (InvocationTargetException) or the shape was wrong
3. Verify the class is on the classpath and the property value matches its FQCN
4. For stateless use, confirm the listener can be instantiated repeatedly (one instance per Session)

Example fix

// before:
props.put("hibernate.session.events.auto", AuditListener.class.getName());
// AuditListener only has AuditListener(AuditService svc)

// after:
public AuditListener() { this.svc = AuditServiceHolder.get(); } // no-arg, lazy collaborator

// validate the class named by hibernate.session.events.auto before boot
String name = (String) props.get("hibernate.session.events.auto");
if (name != null) {
    Class<?> c = Class.forName(name);
    if (!SessionEventListener.class.isAssignableFrom(c))
        throw new IllegalStateException("Not a SessionEventListener: " + name);
    c.getConstructor(); // requires public no-arg ctor
}

static boolean isValidAutoSessionEventListener(String fqcn) {
    try {
        Class<?> c = Class.forName(fqcn);
        return SessionEventListener.class.isAssignableFrom(c) && hasPublicNoArgCtor(c);
    } catch (ReflectiveOperationException e) { return false; }
}

try {
    sessionFactory = metadata.buildSessionFactory();
} catch (HibernateException e) {
    if (e.getMessage() != null && e.getMessage().contains("auto SessionEventListener")) {
        // remove/fix hibernate.session.events.auto; e.getCause() explains the failure
    }
    throw e;
}

When it happens

Trigger: Setting hibernate.session.events.auto=com.acme.MyListener where the class has no public no-arg constructor, is abstract, or its constructor throws when the SessionFactory initializes the auto listener array.

Common situations: Custom listener written with constructor injection only (expects a collaborator); constructor performs logging/metrics setup that fails in certain environments; class name typo or class not deployed; copying the built-in StatisticalLoggingSessionEventListener into a subclass with extra constructor args.

Related errors

• Could not instantiate event listener '{}'
• Unable to instantiate StatementObserver - {}
• Could not instantiate named strategy class [%s]
• Could not instantiate named dialect class [%s]
• Unable to instantiate named dialect resolver [<resolverImplN

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/89b1bb26a9c4973d. Report an issue: GitHub.