Website migrations destroy rankings when 301 redirects are missing, URL structures change without proper canonicals, internal links break, or the new site blocks crawlers. The fix requires a systematic audit before building any new content.
The most common causes
1. Missing 301 redirects
Every old URL needs a 301 redirect to its new equivalent. Without them, Google drops those pages from its index and any backlinks pointing to old URLs lose their value.
2. Changed URL structure without redirects
Even minor changes like adding or removing trailing slashes break every indexed URL if canonicals are not updated to match the new structure.
3. Canonical tags pointing to the old domain
After a domain migration, every canonical must point to the new domain. If they still reference the old domain, Google treats the new site as a duplicate.
4. Robots.txt blocking the new site
Development environments often include Disallow: / to block indexing. If this reaches production, Google cannot crawl anything. Check yoursite.com/robots.txt immediately.
5. Broken internal links
A migration changes URLs but internal links throughout the site often still point to old URL structures, breaking the flow of link equity and signaling poor site quality.
6. XML sitemap not updated
A sitemap still listing old URLs sends crawlers to 404 pages, wasting crawl budget and slowing re-indexation of the new site.
A migration audit works like a proof. Identify every URL on the old site, map it to its new equivalent, verify the 301 is in place, confirm canonicals match, test internal links, verify crawlability. Miss one step and the proof fails.
How to recover
Recovery sequence: audit all 404s in Google Search Console, implement 301 redirects for every broken URL, update internal links sitewide, fix canonical tags, submit updated sitemap, request recrawl. Recovery typically takes 4-12 weeks after all technical fixes are in place.
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UCR Mathematics graduate and 27-year private math tutor who applies systematic, first-principles thinking to every web and SEO problem. Brian diagnoses root causes rather than adding more on top of a broken foundation.