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Site migration: moving without losing your SEO

Most post-redesign traffic drops are not caused by the design. They are caused by unplanned redirects.

A domain change, a redesign, a CMS switch, moving from HTTP to HTTPS — all of these are migrations. And they all suffer the same mistake: the redirect plan is left until last.

Before the move: take inventory

Record the current state before you touch anything. Without it you cannot tell what you lost.

  • A full URL list (from a crawler)
  • Twelve months of query and page data from Search Console
  • Your top 100 pages by traffic
  • Your top 100 pages by external links
  • Current rankings for core terms
  • Current indexed page count

Export and archive it. That is your comparison baseline afterwards.

The URL mapping table

This is the heart of a migration. For every old URL, write its new equivalent. Rules:

  • Every old URL must reach the new one in a single hop — no chains
  • Use 301 (permanent), not 302
  • Pages with no equivalent go to the closest relevant page, not the homepage
  • If there genuinely is no equivalent, return 410 and accept it

Bulk-redirecting everything to the homepage is the most common and most damaging mistake; Google treats it as a soft 404.

Launch day checklist

  1. Verify the new robots.txt is not blocking everything (a leftover Disallow: / from staging is a classic)
  2. Check no noindex tags survived
  3. Sample-test redirects: walk your top 100 URLs one by one
  4. Submit the new sitemap, leave the old one in place for a while
  5. Confirm analytics and Search Console are recording
  6. Check canonicals point at the new URLs

Post-migration monitoring

Check daily for four weeks, then weekly for two months:

  • Crawl errors and 404 growth in Search Console
  • Indexed page count — a dip is expected, recovery is not optional
  • Organic traffic — a temporary 10–20% drop is normal
  • Server logs, to confirm bots are crawling the new URLs

Realistic expectations

Even a well-planned migration loses traffic for two to eight weeks. Full recovery can take three months. Panicking and shipping more changes during that window makes the cause impossible to isolate.

One recommendation: do not change design and URLs at the same time. Move the URL structure first, let it settle, then redesign. That is the only way to know which one caused a problem.