root@server:~# systemctl restart systemd-hostnamed
Job for systemd-hostnamed.service failed because the control process exited with error code.
See "systemctl status systemd-hostnamed.service" and "journalctl -xe" for details.
root@server:~# journalctl -xe
Jul 02 09:34:54 server named[364]: all zones loaded
Jul 02 09:34:54 server named[364]: running
Jul 02 09:35:04 server named[364]: managed-keys-zone: Unable to fetch DNSKEY set '.': timed out
Jul 02 09:35:04 server named[364]: resolver priming query complete
Jul 02 09:35:41 server systemd[1]: Starting Hostname Service...
░░ Subject: A start job for unit systemd-hostnamed.service has begun execution
░░ Defined-By: systemd
░░ Support: https://www.debian.org/support
░░
░░ A start job for unit systemd-hostnamed.service has begun execution.
░░
░░ The job identifier is 453.
Jul 02 09:35:41 server systemd[376]: systemd-hostnamed.service: Failed to set up mount namespacing: Permission denied
Jul 02 09:35:41 server systemd[376]: systemd-hostnamed.service: Failed at step NAMESPACE spawning /lib/systemd/systemd-hostnamed: Permission denied
░░ Subject: Process /lib/systemd/systemd-hostnamed could not be executed
░░ Defined-By: systemd
░░ Support: https://www.debian.org/support
░░
░░ The process /lib/systemd/systemd-hostnamed could not be executed and failed.
░░
░░ The error number returned by this process is ERRNO.
Jul 02 09:35:41 server systemd[1]: systemd-hostnamed.service: Main process exited, code=exited, status=226/NAMESPACE
░░ Subject: Unit process exited
░░ Defined-By: systemd
░░ Support: https://www.debian.org/support
░░
░░ An ExecStart= process belonging to unit systemd-hostnamed.service has exited.
░░
░░ The process' exit code is 'exited' and its exit status is 226.
Jul 02 09:35:41 server systemd[1]: systemd-hostnamed.service: Failed with result 'exit-code'.
░░ Subject: Unit failed
░░ Defined-By: systemd
░░ Support: https://www.debian.org/support
░░
░░ The unit systemd-hostnamed.service has entered the 'failed' state with result 'exit-code'.
Jul 02 09:35:41 server systemd[1]: Failed to start Hostname Service.
░░ Subject: A start job for unit systemd-hostnamed.service has failed
░░ Defined-By: systemd
░░ Support: https://www.debian.org/support
░░
░░ A start job for unit systemd-hostnamed.service has finished with a failure.
░░
░░ The job identifier is 453 and the job result is failed.