Certificates need attention whenever a site moves.
IMMEDIATELY AFTER THE MOVE
Confirm the domain resolves to the new server Run AutoSSL covering the domain, www, all subdomains and mail hostnames Confirm every entry shows a padlock in SSL/TLS Status
THE REDIRECTS
Re-enable Force HTTPS on the new server, since the setting does not migrate Check .htaccess came across and contains the expected rules, with no duplicates Test all four URL forms
THE CONTENT
Run a database search and replace if the domain or scheme changed Check mixed content on several pages Look specifically for references to a staging hostname
Reconnect a mail client and confirm no certificate warning Check clients configured with the old server hostname, which will stop working
CLOUDFLARE
If in use, confirm SSL/TLS is Full (strict) and mail records are DNS-only
VERIFY EXTERNALLY
Run an online SSL checker rather than trusting your own browser, which may have cached the old certificate.
THE STEP MOST OFTEN MISSED
Running AutoSSL at all. Add it to the migration checklist.
