Site Migration
A site migration is any change to a site's domain, URL structure, platform, protocol or design that affects how search engines see it. It is the highest-risk routine event in SEO and the most common cause of sudden traffic collapse.
Why it matters for your rankings
Migrations concentrate every technical risk into a single release. Redirects, canonicals, internal links, structured data and robots directives all change simultaneously, and one error can undo years of accumulated authority.
The pattern of failure is consistent. Traffic drops the week of launch, the cause is investigated for a month, and the redirect map turns out to have been generated automatically without checking that destinations were relevant. Recovery from a bad migration takes far longer than the migration itself. The work that prevents this is unglamorous and entirely front-loaded: a complete URL inventory, a hand-checked redirect map, and a staging environment verified before anything goes live.
How to check it on your site
Inventory every URL first
Crawl the existing site and export all indexable URLs with their traffic and backlink data before making changes.
Build the redirect map by hand
Each old URL needs a genuinely relevant destination. Automated mapping to the homepage destroys equity.
Verify staging before launch
Check robots.txt, noindex tags, canonicals and structured data on staging, and confirm staging itself is blocked.
Monitor daily for a month
Watch Search Console for 404 spikes, indexation drops and crawl errors immediately after launch.