Illegal attempt to associate a collection with two open sessions thrown in Quartz Job I have a Grails 4.0.10 application which is a running registration application. I am getting a Illegal attempt to associate a collection with two open sessions error in a Quartz Job in my application. This is the method in RegistrationService called by PaymentController. It triggers BibAssigner Job at the end. The BibAssigner Job is responsible for assigning bibs to the registrations. RegistrationService @Transactional void activateRegistrations(SaleInvoice invoice){...