Problem
When syncing Epics with Exalate for Jira on-premise, the stories are getting duplicated in case any transition errors occur.
Cause
There were some changes done to the Exalate code in release 5.2.2 and it is required to update the External scripts to avoid the duplication issue.
This will apply to an outdated version of supported scripts, including the following scripts:
- Epic.groovy
- IssueLinks.groovy
- SimpleSprintSync.groovy
- Status.groovy
- SubTask.groovy
Solution
Note: For more information read the list of supported external scripts and update them accordingly.
Replace the following files with the latest versions:
- Update Epic.groovy to the most recent version at Epic.groovy.
- Update IssueLinkSync.groovy to the most recent version at IssueLinks.groovy
- Update SimpleSprintSync.groovy to the most recent version at SimpleSprintSync.groovy - Note: For more information read How to synchronize sprints in Jira Server. 
- Update Status.groovy to the most recent version available at Status.groovy 
- Update SubTask.groovy to the most recent version available at SubTask.groovy