All error codes

invalid_hostname

HTTP 422 Server name is not a valid host name

What happened

The platform did not accept the name you asked for on the server. The name it stored differs from the one you sent, so the rename did not happen.

What to do

Send a name that is valid as a host name - letters, digits, dots and hyphens, starting and ending with a letter or digit - and repeat the request.

Retrying

Fix the request and send it again.

How it arrives

{
    "type": "https://docs.fiberax.com/errors/invalid_hostname",
    "title": "Server name is not a valid host name",
    "status": 422,
    "code": "invalid_hostname",
    "request_id": "a277dcd1ca652c65"
}

Branch your code on code, never on the wording of title.