When you move a domain name, it can take several hours before the change has been propagated throughout the internet. That can prevent you from creating a SSL certificate, due to which you can’t access the site over HTTPS, which is a problem if the site used HSTS.

Before you move:

1. Disable HSTS
2. Set the TTL to a value as low as possible (60 = one minute, 300 = five minutes)
3. Move the site
4. After the TTL has expired , flush the Google DNS https://developers.google.com/speed/public-dns/cache
   (doesn’t flush all name servers around the internet though)
5. Check the DNS Propagation at https://www.whatsmydns.net/