Migration AD Discrepancy

[Tim Simon]

I’m a part of a team working on a data migration of issues from a Jira Server instance into a Jira Data Center instance. We use an AD in Jira Server that is different than the AD configured for Jira Data Center, but contains the same use base.

We are running into issues with data migration due to a discrepancy in AD account configurations. The users are getting dropped from assigned issues and/or duplicate user accounts are being created in Jira Data Center. We believe this is because users in the Jira Server configured AD are represented by a username (e.g. "doej"), but the AD for Jira Data center represents users by an email address (e.g. "john.doe@example.com") so the issue migration is unable to find a matching account for the Jira Server users.

Is there existing documentation or knowledge base pages that can be provided for guidance to resolve this situation so users can be correctly mapped into the Jira Data Center instance and retain existing issue assignments?