Can't change the foreman katello hostname

Problem:
I can’t change the foreman katello hostname, It says:
foreman01.example.local is not a valid fully qualified domain name, please use a valid FQDN and try
again. No changes have been made to your system.

Expected outcome:
** Hostname change complete! **

DNS

Version

1.24.2

Domains

Discovery

Version

1.0.5

HTTPBoot

Version

1.24.2

Pulp

Version

1.5.0

Pulp server version

2.21

Database connection

Messaging connection

Workers

3

Salt

Version

3.1.1

TFTP

Version

1.24.2

TFTP server

false

Templates

Version

1.24.2

kindly advice me on how to change the hostname? or how to skip the checking hostname validation

Thanks in advance.

Kind regards,

Bahram