Error

Changing the domain name in the configuration file and in ejabberd's startup command do not work.

Explanation

Because ejabberd uses Mnesia as its internal database, and because this system stores the Erlang node name into the backup files, you cannot simply change the domain name in the configuration file and in ejabberd's startup command. If you want to migrate from one host to another you have to 'convert' the backups from the old node name to the new one and then restore these converted backups.

Solution

Read the tutorial Migrate Database to Another Host.