Profile migration issue

I have migrated my account to a new machine by exporting my profile and importing the .gz file on my new computer. However, the nickname is not being migrated and I cannot use this nickname on my new computer.

the nickname is in the archive?
What do you call nickname? The one under the avatar or the registered name&

I mean the registered username and I would have hoped that this is in the archive

No. the registered name is on the name server.

The client will retrieve it by making a request on http://ns.jami.net/addr/YOUR_HASH
and http://ns.jami.net/name/YOUR_NAME will also return the result