What is a site migration?
A site migration is moving a website to a new platform, host, domain or set of addresses. When addresses change, each old address needs a permanent redirect to its new match, or visitors and Google reach error pages.
Cited from the66th.com/glossary/site-migration
How a site migration works
Some moves keep every address the same, such as a switch of host. Others change addresses: a new domain, a new platform with its own address patterns, or a new site structure. Google's site move guide asks you to map each old address to its new one, then use that map to plan redirects and update links.
On the new site, canonical tags, internal links and sitemaps (the files that list a site's pages for search engines) point at the new addresses. Each old address returns a permanent server-side redirect, which Google recommends whenever possible.
| Old address | New address | Redirect |
|---|---|---|
| example.com/services.html | example.com/services/ | 301 |
| example.com/drain-cleaning.php | example.com/services/drain-cleaning/ | 301 |
| example.com/blog/?p=42 | example.com/blog/frozen-pipes/ | 301 |
Why Google cares
Google's site move guide tells site owners to expect temporary fluctuation in site ranking during the move.
The same guide asks you to keep the redirects for as long as possible, generally at least one year, and, for a move to a new domain, to submit a Change of Address in Google Search Console, Google's free tool for site owners.
What it means for your business
A migration puts every page's search traffic at stake at once. The risk sits in the details: a missing redirect, a new template that drops the page titles, or a contact form that stops sending after the switch.
It matters most for sites with years of rankings, links and pages. A new site with few visitors has less to lose, and the same checks still apply. Planning and testing a move is part of our technical SEO services.
Common mistakes
- Redirecting every old page to the new home page. Google's site move guide says this can confuse users and might be treated as a soft 404 error, a page Google treats as missing. Point each page to its closest match.
- Building the redirect map from the old sitemap alone. Pages with links or visits can be missing from it, so add addresses from a crawl of the old site and from Search Console.
- Checking only that the new site loads. Test forms, checkout and redirects on the live domain the day you switch.
- Removing redirects a few months after the move. Google's guide asks for at least a year.
Related terms
Sources: Google Search Central, Site moves and migrations, 20 August 2026; Google Search Central, Redirects and Google Search, 14 April 2026.