We will suggest to perform the following steps (for the migration in same server):

1. Backup JIRA Home Directory (include plugins, attachments, and data).
2. Backup Data:
   1. Export out an XML backup via JIRA Backup UI.
   2. Export your Database Dump out.
3. Shutdown JIRA WAR.
4. Install a new JIRA Bin in your server.
5. Run JIRA Configuration Tool.
6. Configure JIRA to use the backup JIRA Home Directory.
7. Configure JIRA to use the current database.
8. Jira を起動します。

If you plan to do migration in another server, please refer our Migrating JIRA to Another Server article.

 We recommend to test this changes in Staging Environment.