Something changed in Grails 3 and how datasources are configured. If you have datasources defined like this: dataSources: dataSource: pooled: true jmxExport: true driverClassName: org.h2.Driver username: sa password: dbCreate: create-drop url: jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE secondary: pooled: true ...