hibernate/hibernate-orm · critical · UnsupportedOperationException

The {storageEngine} storage engine is not supported

Error message

The {storageEngine} storage engine is not supported

What it means

MySQLLegacyDialect.determineStorageEngine() resolves the storage engine from the 'hibernate.dialect.storage_engine' setting. Only the values 'innodb' and 'myisam' (case-insensitive) are recognized; any other value falls through to UnsupportedOperationException('The <value> storage engine is not supported'). The check runs while the dialect determines column types/DDL, so it typically aborts SessionFactory bootstrap.

Source

Thrown at hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/MySQLLegacyDialect.java:236

		getDefaultProperties().setProperty( Environment.MAX_FETCH_DEPTH, "2" );
	}

	private MySQLStorageEngine createStorageEngine() {
		String storageEngine = Environment.getProperties().getProperty( Environment.STORAGE_ENGINE );
		if (storageEngine == null) {
			storageEngine = System.getProperty( Environment.STORAGE_ENGINE );
		}
		if (storageEngine == null) {
			return getDefaultMySQLStorageEngine();
		}
		else if( "innodb".equalsIgnoreCase( storageEngine ) ) {
			return InnoDBStorageEngine.INSTANCE;
		}
		else if( "myisam".equalsIgnoreCase( storageEngine ) ) {
			return MyISAMStorageEngine.INSTANCE;
		}
		else {
			throw new UnsupportedOperationException( "The " + storageEngine + " storage engine is not supported" );
		}
	}

	@Override
	protected String columnType(int sqlTypeCode) {
		switch ( sqlTypeCode ) {
			case BOOLEAN:
				// HHH-6935: Don't use "boolean" i.e. tinyint(1) due to JDBC ResultSetMetaData
				return "bit";

			case TIMESTAMP:
				return getMySQLVersion().isBefore( 5, 7 )
						? "datetime" : "datetime($p)";
			case TIMESTAMP_WITH_TIMEZONE:
				return getMySQLVersion().isBefore( 5, 7 )
						? "timestamp" : "timestamp($p)";
			case NUMERIC:
				// it's just a synonym

View on GitHub (pinned to fad1729dce)

Solutions

1. Set the property to innodb or myisam (exact values, matched case-insensitively) — innodb is the right choice when you need transactions/foreign keys
2. Remove the hibernate.dialect.storage_engine property entirely so the dialect default (getDefaultMySQLStorageEngine()) applies
3. Migrate off MySQLLegacyDialect to the current org.hibernate.dialect.MySQLDialect and drop the legacy-specific property

Example fix

# before (persistence.xml)
<property name="hibernate.dialect.storage_engine" value="rocksdb"/>

# after
<property name="hibernate.dialect.storage_engine" value="innodb"/>
<!-- or omit the property to use the dialect default -->

// validate before building the SessionFactory
String engine = configuration.getProperty("hibernate.dialect.storage_engine");
if ( engine != null
        && !"innodb".equalsIgnoreCase(engine.trim())
        && !"myisam".equalsIgnoreCase(engine.trim()) ) {
    throw new IllegalStateException(
        "hibernate.dialect.storage_engine must be 'innodb' or 'myisam', got: " + engine);
}

When it happens

Trigger: Setting the configuration property hibernate.dialect.storage_engine (Environment.STORAGE_ENGINE) to anything other than innodb or myisam while using MySQLLegacyDialect — e.g. 'rocksdb', 'memory', a trailing-whitespace or misspelled value like 'InnoDB ' handled strictly, or a placeholder copied from another project.

Common situations: Copying persistence.xml/application.yml between projects with different engines; setting the property for a newer MySQLDialect profile (which expects different handling) and then running tests on the legacy dialect; CI config injecting an env-based engine value that is empty or misspelled.

Related errors

• Could not instantiate event listener '{}'
• Unable to instantiate StatementObserver - {}
• No ServiceRegistry was passed to Configuration#buildSessionF
• illegal value for configuration setting 'hibernate.connectio
• Could not instantiate named dialect class [%s]

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/c8f0f55b591086bd. Report an issue: GitHub.