hibernate/hibernate-orm · error · IllegalArgumentException

null is not a valid generator name

Error message

null is not a valid generator name

What it means

InFlightMetadataCollectorImpl.getIdentifierGenerator(name) performs a map lookup of named id-generator definitions and rejects a null name up front with IllegalArgumentException 'null is not a valid generator name'. It means caller code passed an unresolved null generator name into the lookup during metadata processing; it is not a 'generator not found' error (a missing name would just return null).

Source

Thrown at hibernate-core/src/main/java/org/hibernate/boot/internal/InFlightMetadataCollectorImpl.java:626

	@Override
	public void addFetchProfile(FetchProfile profile) {
		if ( profile == null || profile.getName() == null ) {
			throw new IllegalArgumentException( "Fetch profile object or name is null: " + profile );
		}
		final var old = fetchProfileMap.put( profile.getName(), profile );
		if ( old != null ) {
			BOOT_LOGGER.duplicatedFetchProfile( profile.getName() );
		}
	}


	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	// identifier generators

	@Override
	public IdentifierGeneratorDefinition getIdentifierGenerator(String name) {
		if ( name == null ) {
			throw new IllegalArgumentException( "null is not a valid generator name" );
		}
		return idGeneratorDefinitionMap.get( name );
	}

	@Override
	public java.util.Collection<Table> collectTableMappings() {
		final ArrayList<Table> tables = new ArrayList<>();
		for ( Namespace namespace : getDatabase().getNamespaces() ) {
			tables.addAll( namespace.getTables() );
		}
		return tables;
	}

	@Override
	public void addIdentifierGenerator(IdentifierGeneratorDefinition generator) {
		if ( generator == null || generator.getName() == null ) {
			throw new IllegalArgumentException( "Id generator object or name is null" );
		}

View on GitHub (pinned to fad1729dce)

Solutions

1. Trace the caller in the stack trace and resolve a real generator name before the lookup
2. Guard the call: if the name is null, apply a default strategy instead of calling with null
3. Fix the underlying mapping so the generator definition has a name

Example fix

// before
var def = collector.getIdentifierGenerator(generatorName); // generatorName is null

// after
if (generatorName == null) {
    throw new IllegalArgumentException("mapping is missing a generator name: " + mapping);
}
var def = collector.getIdentifierGenerator(generatorName);

if (name == null || name.isBlank()) {
    throw new IllegalArgumentException("generator name missing in mapping: " + mapping);
}
return collector.getIdentifierGenerator(name);

static boolean isQueryableGeneratorName(String name) {
    return name != null && !name.isBlank();
}

When it happens

Trigger: Programmatic or integration code calling getIdentifierGenerator(null) - typically a generator-name variable that was never set, or mapping processing that flows a mapping without a generator name into the lookup (InFlightMetadataCollectorImpl.java:626-629).

Common situations: Custom id-generator handling in integrations; upgrades where generator-name resolution changed and now yields null; mappings whose <generator> element lacks a usable name.

Related errors

• Id generator object or name is null
• Filter definition object or name is null: %s
• Fetch profile object or name is null: %s
• null is not a valid query name
• The specified package name cannot be null

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/747d7a0fb8eff7d8. Report an issue: GitHub.