A site migration is one of the few times a business can lose meaningful search traffic from a purely technical mistake, with no change in content quality at all. The good news is that the mistakes are well understood and avoidable.
Map every URL before you move anything
A full inventory of existing URLs, with a 301 redirect planned for each one to its new equivalent, is the single most important step. Search engines follow redirects and transfer ranking signal through them — a migration with no redirect map simply throws that signal away.
Keep content and structure as stable as you can
A migration is not automatically also the right moment for a full content rewrite and information-architecture overhaul. Changing the URL, the content, and the site structure all at once makes it far harder to tell which change caused any ranking movement afterward.
Don’t let staging get indexed
A staging copy of the new site, accidentally left crawlable, can create duplicate content issues or even get indexed in place of the real site. Password-protecting or noindexing staging environments is a small step that prevents a genuinely damaging mistake.
Submit the new sitemap and monitor closely
After launch, submitting an updated sitemap and watching Search Console for crawl errors or sudden ranking drops in the following weeks lets you catch and fix problems while they’re still small, rather than months later when traffic has already dropped.
Expect a temporary dip, worry about a permanent one
Some short-term fluctuation during re-indexing is normal and not a sign anything went wrong. A sustained drop, weeks after launch, usually points to a specific technical issue — broken redirects, duplicate content, or a noindex tag left on by mistake — that’s worth investigating directly.