Zero-Downtime Website Migration Checklist (2026)

Why does migration risk downtime at all?

Moving a website means copying it to a new server and pointing your domain there, and the gap between those steps is where things break. If you switch the domain before the new copy is ready and tested, visitors hit a broken or missing site. DNS changes also take time to spread across the internet, so for a window some users see the old host and some see the new one. The zero-downtime approach removes these risks by preparing fully, testing on the new host first, and shortening DNS propagation. Work through the stages below in order and your visitors should never notice the move.

Stage 1: Before you move (preparation)

Preparation is where most failed migrations are actually lost, so do not rush it. Back everything up, document your current setup, and reduce DNS TTL so the later switch propagates fast.

• Take a full backup of all website files and the database, and download a copy locally.
• Note your current PHP version, plugins, and any server settings to replicate.
• List every domain and subdomain, plus email accounts tied to the host.
• Lower DNS TTL to 300 seconds at least 24-48 hours before the switch.
• Confirm the new host's specs match or beat the old one (PHP, storage, SSL).
• Tell stakeholders the migration window and pick low-traffic hours.

Stage 2: The move and testing

Copy the site to the new host and test it thoroughly using a temporary URL or hosts-file trick before any public switch. Nothing goes live until the new copy works exactly like the old one.

• Upload all files and import the database to the new server.
• Update configuration files (database credentials, site URLs) as needed.
• Install and validate the SSL certificate on the new host.
• Preview the site on the new server via a temporary URL or local hosts file.
• Test every key page, menu, image, form, and checkout flow.
• Re-check internal links and confirm no references point to the old server.

Stage 3: Go live (the DNS switch)

Only switch DNS once the new site is fully tested and working. Pick a quiet traffic window, update the records, and keep the old host running in parallel until propagation completes.

• Put the original site in temporary read-only or maintenance mode if it accepts new data.
• Update the A record / nameservers to point the domain at the new host.
• Keep the old host live for 48-72 hours while DNS propagates worldwide.
• Monitor traffic and error logs on the new host during the switch.
• Restore the low TTL to a normal value (e.g. 3600s) once stable.

Stage 4: Post-launch verification

The job is not done when DNS flips; verify everything works on the live new host and that search engines and analytics still track correctly. Catch issues in the first 48 hours, not weeks later.

• Confirm the padlock (SSL) loads on every page and http redirects to https.
• Test contact forms, logins, and payment/checkout end to end.
• Check 301 redirects and that old URLs still resolve correctly.
• Verify analytics and tracking pixels are firing on the new host.
• Re-submit the sitemap in Google Search Console and watch for crawl errors.
• Keep backups for at least 2 weeks before fully decommissioning the old host.