[ERROR] Exception occured: ISPConfigOSException -> Host name is no FQDN. (/ispconfig.ai.php:15)

I get this error when i try to install ispconfig.
Can you tell me how to fix it?
[ERROR] The host name artyman.com of your server is no fully qualified domain name (xyz.domain.com). Please check it is correctly set. (/lib/os/class.ISPConfigDebianOS.inc.php:548)
[ERROR] Exception occured: ISPConfigOSException -> Host name is no FQDN. (/ispconfig.ai.php:15)

 

Thanks, now I get this error. Can you tell me whats wrong?
[ERROR] Exception occured: ISPConfigOSException -> Command hostname -f 2>&1 failed. (/ispconfig.ai.php:15)

 

After reboot
root@mydomain:~# hostname -f
mydomain.com

I change the hostname but when I reboot the hostname change back to mydomain.com

 

I get Permission denied for /etc/hosts.
root@mydomain:~# /etc/hosts
-bash: /etc/hosts: Permission denied

 

Yes I am root.
when I type: nano /etc/hosts
I get:
127.0.0.1 localhost.localdomain localhost
173.214.161.149 server1.mydomain.com.com server1

::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

 

When I type: nano /etc/hostname
I get: mydomain.com

 

When I change it and reboot, it changes back to mydomain.com

 

I reinstall but now I get this error :
[ERROR] Exception occured: ISPConfigOSException -> Command mount -o remount / 2>&1 && quotaoff -avug 2>&1 && quotacheck -avugm 2>&1 && quotaon -avug 2>&1 failed. (/ispconfig.ai.php:15)

Can you help me solve the issue?

 

I am assuming you are using ISPConfig autoinstall?
https://www.howtoforge.com/ispconfig-autoinstall-debian-ubuntu/
Chapter 2 of the instructions tells how to set up hostname. It also show commands

Code:

hostname
hostname -f

for checking hostname and domain name is set up properly.
The autoinstall works well, but it must be started on a freshly installed minimal server of Debian or Ubuntu, which is configured following the instructions in the autoinstall tutorial. If these conditions are not met the autoinstaller does not work.

If I were you, I would start again from the beginning, with a fresly installed OS. Now you know what to do and are more likely to successfully install ISPConfig.