Why do I get this error: "The name of your computer is already in use on this network"?
Open a terminal.
Type the following command to change the primary hostname of your Mac:



  This is your fully qualified hostname, for example, myMac.domain.com


 sudo scutil --set HostName &lt;new host name&gt;



Type the following command to change the Bonjour hostname of your Mac:



  This is the name usable on the local network, for example myMac.local.


sudo scutil --set LocalHostName &lt;new host name&gt;



If you also want to change the computer name, type the following command:



  This is the user-friendly computer name you see in Finder, for example
  myMac.


 sudo scutil --set ComputerName &lt;new name&gt;



Flush the DNS cache by typing:

dscacheutil -flushcache

Restart your Mac