After a Case is reopened on a KIE Server, the operation caseClient.getCaseInstance(CONTAINER_ID, caseId); fails with 404 return code/CaseNotFoundException on the server side. This is because there are two entries for the specified caseId (correlationKey) and Hibernate 5.3.6 no longer handles duplicates correctly when calling getSingleResult(). More info can be found here: https://hibernate.atlassian.net/browse/HHH-13245