DB connectivity fails in grails 5 application with error creating hibernateDatastore

Solution 1:

If you have @Transactional on a domain class (which there is no good reason to do) that will result in a property named transactionManager being added to the class. That is required in order for the transaction management logic to be carried out. The problem is that properties in a domain class are by default mapped to the database unless they are configured as transient.

You should remove the @Transactional annotation from the domain class and move any transactional logic wherever transactions are being managed, which frequently is in a transactional Service.