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Once you have the entities.xml file extracted from the Jita Jira Cloud backup archive and the JSON file containing the exported app data from Cloud, you can proceed with the import of this data in the Jira Data Center instance.
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Log in as an admin to your Jira Data Center instance
Navigate to Administration > Project Team > Import From Cloud page
For Project Team Exported Data From Cloud, choose the JSON file generated previously
For Jira Cloud Exported Entity XML File, choose the entities.xml file extracted from the Jira backup for Cloud archive
You can check the Merge data option if you have imported the data once and want to re-import a file that now contains additional user custom fieldsdata. This will allow importing the new custom fields and their values.
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data to be imported, while the existing data will be preserved.
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Click Start Import to begin the import process
The import process will display a progress bar tracking the import of custom fields and associated user properties
In case the application is unable to map some of the users from the import file to the local Data Center users directory, it will display a notification message and once the import process is completed it will show a Download button that allows you to download the list of these users.