What is a site migration?
Search engines know a site as a set of addresses, each with its own history of links, rankings and content. A migration is any change that alters that set significantly. Moving to a new domain is a migration. So is switching from HTTP to HTTPS, rebuilding on a new content management system, merging two sites into one, changing the URL structure, moving to a new host, or redesigning in a way that changes pages, content and internal links.
Some migrations change one thing and some change everything at once. The risk rises with each element changed, because when traffic drops afterward it becomes hard to tell which change caused it. A careful migration changes as little as possible in one step and moves the rest in a later one.
Why it matters
Why a site migration matters
Done well, a migration is invisible to visitors and search engines: old addresses lead to new ones, rankings carry across and traffic dips briefly, if at all. Done badly, it can erase years of search visibility in a weekend. Pages vanish, links from other sites point at errors, and search engines treat the new site as a stranger. Recovery can take months, and some of what was lost never returns. Most migrations go wrong for the same reason: the team planned the new site carefully and the move itself barely at all.
In practice
How a site migration works in practice
- 01
First, an inventory. Every URL on the old site is crawled and listed with its traffic, rankings and inbound links, so the team knows which pages matter. That list becomes a redirect map: each old address paired with its closest new equivalent, page to page, never everything to the homepage.
- 02
Second, the new site is built and tested on a staging server that search engines cannot see. Redirects, titles, meta descriptions, canonical tags, structured data and internal links are checked against the old site, along with page speed and analytics tracking, before anything is switched.
- 03
Third, the launch, timed for a quiet period. The redirects go live with the new site, the new sitemap is submitted to Google Search Console and Bing Webmaster Tools, and for a domain change Google's Change of Address tool is used. The staging block on search engines is removed, a step forgotten more often than anyone admits.
- 04
Fourth, monitoring for weeks, not days. Crawl errors, indexed pages, rankings, traffic and conversions are compared with the baseline, broken redirects are fixed as they appear, and the old domain is kept and renewed for years so its redirects keep working.
Watch out
What people get wrong about site migrations
Redirecting every old page to the homepage, which search engines treat much like a missing page. Second, combining a domain change, a new platform, new URLs and new content in one launch, so that when traffic falls nobody can tell why. Third, letting the old domain expire after a year, which breaks every redirect and every link that still points to it. And launching on a Friday afternoon, with nobody watching on Saturday.
