hibernate/hibernate-orm · error · HibernateException

Unable to generate set of all hints - {}

Error message

Unable to generate set of all hints - {}

What it means

Thrown by HintsCollector.applyHints() as a HibernateException when reflection (field.get) fails with IllegalAccessException while collecting every public static String field whose name starts with HINT_ from a hints-holding class. HintsCollector builds the set of all available query hints by reading HINT_ constants from classes such as org.hibernate.jpa.HibernateHints, AvailableHints, etc.; a class whose package or class is not open to hibernate-core under strict access checks makes the read fail.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/jpa/internal/HintsCollector.java:46

	@Nonnull
	private static Set<String> buildHintsSet() {
		final HashSet<String> hints = new HashSet<>();
		applyHints( hints, HibernateHints.class );
		applyHints( hints, SpecHints.class );
		return unmodifiableSet( hints );
	}

	private static void applyHints(@Nonnull HashSet<String> hints, @Nonnull Class<?> hintsClass) {
		for ( final var field : hintsClass.getDeclaredFields() ) {
			if ( field.getName().startsWith( "HINT_" )
					&& field.getType().equals( String.class ) ) {
				// the field's value is the hint name
				try {
					hints.add( (String) field.get( hintsClass ) );
				}
				catch (IllegalAccessException e) {
					throw new HibernateException(
							"Unable to generate set of all hints - " + hintsClass.getName(),
							e
					);
				}
			}

		}
	}
}

View on GitHub (pinned to fad1729dce)

Solutions

1. In a modular app, add 'opens <hints.package> to hibernate.core' (or open the package) in module-info.java.
2. Avoid passing non-public custom classes that define HINT_ constants into the hints collection API.
3. Ensure hibernate-core is loaded by the same classloader layer as the hints classes in shaded/embedded setups.
4. Run with --add-opens as a temporary diagnostic to confirm access is the issue.

Example fix

// before
module com.acme.app {
    requires hibernate.core;
    // package not opened
}

// after
module com.acme.app {
    requires hibernate.core;
    opens com.acme.hints to hibernate.core;
}

// in a JPMS app, assert readability before boot
Class<?> hints = Class.forName("org.hibernate.jpa.HibernateHints");
Field f = hints.getDeclaredField("HINT_TIMEOUT");
f.setAccessible(true); // will throw InaccessibleObjectException if the package is not open

When it happens

Trigger: Running on a JDK/classloader with strong encapsulation (JPMS, Java 17+ --illegal-access=deny defaults, restricted containers) where the hints class's declaring package does not open access to Hibernate; or a custom class with HINT_-prefixed String fields passed into the collector that is non-public.

Common situations: JPMS-modularized applications that do not open the package containing an extended hints class; custom builds shading/relocating Hibernate classes so the reflection targets end up non-public; security managers or container policies denying reflective field access.

Related errors

• Could not instantiate entity
• Unable to create AttributeConverter instance
• The {} class [{}] could not be instantiated
• Class '<componentClassName>' is an '@Embeddable' type and ma
• Property '<propertyName>' may not be annotated '@BatchSize'

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/cf5d141fb9990f22. Report an issue: GitHub.