E [/usr/local/cpanel/scripts/fixetchosts] The hostname example.hostname is not valid.

Symptoms

You may see the following error when performing a cPanel update, or you may have received a notification regarding cPanel update failures containing the following error:

...
E [/usr/local/cpanel/scripts/fixetchosts] The hostname example.hostname is not valid.
E [/usr/local/cpanel/scripts/fixetchosts] The “/usr/local/cpanel/scripts/fixetchosts”
command (process 2117) reported error number 2 when it ended.
...

Description 

This occurs when /usr/local/cpanel/scripts/fixetchosts detects an invalid hostname during cPanel updates.

Workaround

Configure a valid hostname in WHM >> Networking Setup >> Change Hostname. For information on effective hostname usage, please see:

Effective Hostname Usage With cPanel & WHM