Upgrading from OTRS 3.x to OTRS 4

• The customfield ID of the 'OTRSTicketID' field has to be set in the configuration page (Core::REST).
  
  
• In JIRA the assignee and reporter have to be on the Create and Edit screens for the selected issuetype and project. The same goes for the customfield 'OTRSTicketID' and all other JIRA fields in the mapping from OTRS to JIRA.