From the dashboard
Go to System → Import / Export and upload the file. Before you confirm, the dashboard shows the list of configurations it is about to import and whether each is new or an update. Review that list, and pay attention to anything marked as an update that you did not intend to change.From the API
Post the file to the import endpoint. Adddry-run=1 to validate the file without importing it.
valid flag and the results array.
See the API documentation.