A Site Migration Traffic Drop We Could Have Prevented

The migration was a replatform — moving a mid-size content site from a legacy CMS to a modern stack, with a new URL structure as part of the redesign. Organic traffic dropped 34% within three weeks of launch. By the time we were brought in to diagnose it, the client had already lost a month of search visibility they weren't going to get back quickly.

What we found when we dug in

The redirect map covered the obvious top pages but missed roughly 15% of URLs that had meaningful but not top-tier traffic — pages nobody flagged as important enough to carefully map, that collectively represented a real chunk of organic sessions. Several redirects that did exist were chained (old URL to an intermediate URL to the final new URL) rather than direct, diluting the signal passed through. And the new XML sitemap was generated before the final URL structure was locked, so it was submitted to Search Console pointing partially at URLs that no longer existed by launch day.

A migration doesn't lose traffic because search engines punish redesigns. It loses traffic because somebody's redirect map had gaps nobody checked for before launch.

The checklist that would have caught every one of these

• Crawl the entire old site and cross-reference every URL that received any organic traffic in the prior 12 months against the redirect map — not just the obviously important pages.
• Verify every redirect resolves directly to its final destination in a single hop, not through an intermediate URL.
• Regenerate and validate the XML sitemap against the actual live URL structure after launch, and resubmit it immediately rather than relying on a pre-launch version.
• Monitor Search Console coverage reports daily for the first two weeks post-launch specifically for a spike in 404s or 'submitted URL not found' errors, which is the earliest signal something's wrong.

Recovery took about ten weeks once we closed the redirect gaps and fixed the sitemap, and the client never fully regained the lost month's worth of momentum — some rankings that dropped during the gap were picked up by competitors in that window and didn't fully return. All of it was preventable with a checklist that takes a day to run properly, and none of it required anything beyond basic diligence.