Site Migration: How to Succeed Without Losing SEO Traffic

A migration covers any major change to a site: new domain, move to HTTPS, CMS change, design overhaul, new URL structure. Poorly prepared, it can cause a significant traffic drop. Well prepared, it goes through without lasting damage.

Before the migration

• Define goals and scope: what is changing, and why?
• Measure the starting point: organic traffic, rankings, most visited pages, pages that receive links, indexing. This is your benchmark.
• List all current URLs with a crawler, the sitemap and Search Console.
• Prepare the URL mapping: for each old address, the equivalent new one, as close as possible in content.
• Keep what works: content, titles, tags, structured data, internal linking. Changing fewer things at once reduces risk.
• Test on a staging environment, protected by a password rather than only by robots.txt, to avoid accidental indexing.

During the migration

• Set up server-side 301 redirects, page by page, from each old URL to its new equivalent. Avoid redirecting everything to the homepage.
• Remove staging blocks: a forgotten noindex or Disallow: / is a classic, costly mistake.
• Update internal links, canonical tags, hreflang tags and the sitemap to use the new addresses.
• Check the title tags, meta descriptions, headings and structured data of the new version.
• Install tracking (Analytics, tags) on the new version.
• Choose a low-traffic period for go-live, with a team available.

Special case: domain change

• Add the new domain to Google Search Console.
• After the redirects, use the change of address tool in the old property. It is only for a domain change, not for an HTTP to HTTPS move nor a simple URL change within the same domain.
• Keep the old domain and its redirects.

After the migration

• Test redirects with a crawler: no 404 errors, no chains or loops.
• Submit the new sitemap in Search Console. You can temporarily keep the old one to help Google discover the redirects.
• Monitor indexing, crawl errors, impressions and clicks, day by day in the first weeks.
• Compare with the starting state, accounting for seasonality.
• Fix quickly any errors: broken links, forgotten pages, missing content.
• Ask for updates to important external links to the new address when possible.
• Keep redirects at least a year, ideally longer.

What to expect

Slight temporary fluctuations are normal after a migration, while Google crawls and processes the new addresses. A lasting or significant drop signals a problem to identify quickly: missing redirects, modified content, indexing block, degraded performance.

The most frequent mistakes

• Forgetting or badly mapping redirects.
• Changing the domain, URLs, content and design all at once.
• Leaving the staging noindex in production.
• Deleting pages that brought traffic or links with no equivalent.
• Neglecting monitoring after go-live.

A successful migration is above all the result of a rigorous inventory and careful URL mapping. Allow time for preparation: it is what protects your traffic.