A website migration is one of the few moments when a business can lose years of organic growth in a single weekend. New platform, new design, new URLs: everything looks better, and then traffic quietly slides for a month before anyone notices.
The good news is that almost every migration loss is preventable. The bad news is that the causes are rarely the ones on a standard launch checklist. Here is the process we use, split into before, during and after launch.
Before launch: map everything that earns traffic
- Export every URL that matters. Pull landing pages with organic sessions from GA4, pages with clicks from Search Console, and every URL with backlinks. That list is what you must not lose.
- Build a one-to-one redirect map. Each old URL should 301 to its closest new equivalent, not to the homepage. Redirecting everything to the homepage is treated as a soft 404.
- Keep titles and content stable. Change the platform or the content, not both at once. If traffic drops, you need to know which change caused it.
- Benchmark. Record indexed pages, top keywords, organic sessions and Core Web Vitals so you can compare after launch.
During launch: check what crawlers see, not just what people see
A page can look perfect in a browser and still tell Google it does not exist. In our phantom 404s case study, a caching rule returned 404 status codes on fully working product pages, and 40% of organic traffic disappeared before anyone looked at the raw headers.
- Check raw HTTP status codes with your browser’s Network tab or curl, not just the rendered page
- Crawl the old URL list and confirm every redirect is a single 301 hop to a 200 page
- Confirm robots.txt and noindex tags from staging have been removed
- Submit the new XML sitemap in Search Console on launch day
The rule we never skip
Test a sample of important URLs at the HTTP level after every CDN, caching or platform change, even when the change seems unrelated to SEO.
After launch: watch the right two numbers
When traffic drops, separate the two things a drop can be made of: fewer pages earning clicks (an indexing problem) or fewer clicks per page (a relevance problem). Plot indexed pages from the Page Indexing report against sessions per landing page. If pages are falling out of the index while per-page performance holds steady, look at status codes, canonicals and redirects before touching content.
- Check Search Console’s Page Indexing report daily for the first two weeks
- Fix redirect chains and any 404s on URLs that had traffic or links
- Re-check Core Web Vitals on the new templates
- Compare top keywords and landing pages against your benchmark weekly
The short version
Map what earns traffic, redirect it one-to-one, verify what crawlers actually receive, and monitor indexing as closely as you monitor sales. If you are planning a relaunch and want a second pair of eyes, book a free consultation and we will review your migration plan.
