Unable to receive WAL files with barman

When you run into a problem like this one, be sure to double-check your logs, the barman check command, and make sure you set a barman cron entry to start barman receive-wal. That needs to be running before you can execute barman switch-wal and finish your setup. =)

What versions of PostgreSQL and Barman are you using?

Before PG 9.3, there were no WAL files ending in FF, it went from FE to 00.

It seems likely you are using PG < 9.3, but your version of Barman is not expecting that.