hibernate/hibernate-orm · error · UnknownUnwrapTypeException

Cannot unwrap to requested type [{}]

Error message

Cannot unwrap to requested type [{}]

What it means

Error "Cannot unwrap to requested type [{}]" thrown in hibernate/hibernate-orm.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/DriverManagerConnectionProvider.java:337

				dbInfo.getIsolationLevel(),
				dbInfo.getPoolMinSize(),
				dbInfo.getPoolMaxSize(),
				dbInfo.getJdbcFetchSize()
		);
	}

	@Override
	public boolean isUnwrappableAs(@Nonnull Class<?> unwrapType) {
		return unwrapType.isAssignableFrom( DriverManagerConnectionProvider.class );
	}

	@Override
	public <T> T unwrap(@Nonnull Class<T> unwrapType) {
		if ( unwrapType.isAssignableFrom( DriverManagerConnectionProvider.class ) ) {
			return unwrapType.cast( this );
		}
		else {
			throw new UnknownUnwrapTypeException( unwrapType );
		}
	}

	protected int getOpenConnections() {
		return state.getPool().getOpenConnectionCount();
	}

	protected void validateConnectionsReturned() {
		final int allocationCount = getOpenConnections();
		if ( allocationCount != 0 ) {
			CONNECTION_INFO_LOGGER.connectionLeakDetected( allocationCount );
		}
	}

	protected void validateConnections(ConnectionValidator validator) {
		state.validateConnections( validator );
	}

View on GitHub (pinned to fad1729dce)

Solutions

1. Only unwrap to types the DriverManagerConnectionProvider actually implements
2. Avoid unwrap() calls with unrelated target types

When it happens

Trigger: Thrown at hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/DriverManagerConnectionProvider.java:337 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/62e34c76a83da99e. Report an issue: GitHub.