Quick answer: An SEO migration goes well when you treat it as a project with three phases. Before launch, crawl the old site, record rankings and traffic, and map every old URL to its new home. At launch, put 301 redirects live, keep content and metadata intact, update the XML sitemap and use Search Console’s Change of Address tool if the domain is changing. After launch, crawl again, watch crawl errors and index counts, and fix problems quickly. Most traffic losses come from missing redirects and pages dropped without anyone noticing.
A site migration is any change big enough to alter how search engines see your site: a new domain, a new CMS, a redesign that changes URLs, a move to HTTPS, or merging two sites. Each of these can be done without lasting damage. Each can also wipe out years of search traffic if the details are skipped. The difference is almost always planning.
Types of migration and their risk
Not every move carries the same risk. It helps to be clear about what is actually changing.
- Protocol change (HTTP to HTTPS): low risk if redirects are done properly. Our HTTPS migration guide covers this one in detail.
- Redesign on the same URLs: moderate risk. The URLs stay, but content, internal links and templates change.
- Platform change: moderate to high risk. Moving from one CMS to another usually changes URL patterns, category structures and how metadata is stored.
- Domain change: high risk. Every URL changes, and search engines have to transfer what they know about the old domain to the new one.
- Site merge or split: highest risk, because content is being combined, removed or moved between domains at the same time.
The more of these you combine in a single launch, the harder it is to diagnose problems afterwards. If you can, change one thing at a time. Moving to HTTPS a few weeks before a redesign, for example, makes each step easier to monitor.
Phase 1: Before the move
Benchmark where you are
You cannot judge whether a migration worked without a clear before picture. Record:
- Organic sessions and landing pages from Google Analytics for at least the last few months.
- Top queries, clicks and impressions from the Search Analytics report in Search Console.
- Rankings for your most important keywords.
- The number of pages indexed, from Search Console’s index status report.
- Pages with the most external links, from your backlink tool of choice.
Save this data somewhere outside the analytics tools. If tracking breaks during launch, you still want the comparison.
Crawl the old site
Use a crawler such as Screaming Frog to export every URL on the current site, along with titles, meta descriptions, H1s, canonical tags and status codes. Combine that list with URLs from your XML sitemap, Google Analytics landing pages and your backlink data. Crawlers only find pages that are linked internally, and older pages that still earn traffic or links are often orphaned.
Build the redirect map
This is the single most important document in the whole project. It is a spreadsheet with two columns: the old URL and the new URL it should redirect to.
Rules for a good map:
- One to one where possible. Each old page should point to the closest equivalent new page, not to the homepage.
- Use 301 redirects. A 301 tells search engines the move is permanent, and Google has said 301s pass most of a page’s ranking signals.
- Avoid chains. Old URL to new URL in one hop. If you already have redirects from a previous migration, update them to point straight at the final destination.
- Decide on removed pages deliberately. If a page has no equivalent and no value, a 404 or 410 is fine. If it has links or traffic, find the best related page.
Keep what works
A migration is tempting as a chance to rewrite everything. Be careful. Pages that rank well have titles, headings and body content that search engines understand. If you change the URL, the template and the content all at once, you make it much harder for that page to hold its position. Carry over titles, meta descriptions and the main content of your best pages, and improve them after the move has settled.
Test on a staging site
Build the new site on a staging server that is blocked from search engines, either with password protection or a robots.txt disallow. Then:
- Crawl the staging site and compare it with the old crawl. Look for missing pages, duplicate titles and broken internal links.
- Test a sample of redirects, including your top landing pages and most linked pages.
- Check canonical tags point to the new production URLs, not staging.
- Make sure analytics and Google Tag Manager are installed on every template.
Phase 2: Launch day
Pick a quiet time. Launching on a Friday afternoon or just before your busiest season is asking for trouble.
Launch checklist
- Put the new site live and the redirects in place at the same moment.
- Remove the staging block. A robots.txt disallow or noindex tag left over from staging is one of the most common and most damaging mistakes.
- Check canonical tags, hreflang tags if you use them, and the robots.txt file.
- Submit the new XML sitemap in Search Console.
- If the domain has changed, verify the new domain in Search Console and use the Change of Address tool from the old property.
- Test your top 50 to 100 URLs by hand or with a crawler in list mode to confirm each one returns a 301 to the right page and the destination returns a 200.
Keep the old domain
If you are changing domains, keep the old domain registered and the redirects running for a long time, ideally permanently. Links from other sites point at the old URLs and will continue to do so for years. Letting the old domain lapse throws all of that away.
Phase 3: After the move
First week
- Crawl errors: check Search Console daily for new 404s and server errors. Add redirects for any old URLs you missed.
- Index status: expect the old site’s index count to fall and the new one to rise. A sudden drop on both is a warning sign.
- Analytics: confirm data is flowing and that organic traffic is being recorded correctly.
- Internal links: update links in content, menus and footers to point at the new URLs directly rather than relying on redirects.
First few months
Some fluctuation is normal for a few weeks while search engines recrawl and reprocess the site. Compare organic landing pages against your benchmark. Pages that lost traffic deserve a closer look: is the redirect right, is the content still there, did the title change?
Ask the sites that link to you most often to update their links to the new URLs. It is not essential if redirects are in place, but direct links are cleaner and do not depend on redirects staying live forever.
Common migration mistakes
- Redirecting everything to the homepage. Search engines treat this much like a 404 for the original page, and visitors land somewhere unhelpful.
- Forgetting images and PDFs. If your images or documents rank or have links, they need redirects too.
- Leaving noindex in place. Check this on launch day and again a day later.
- Changing too much at once. New domain, new URLs, new content and new design together make problems very hard to trace.
- Dropping pages without checking. A page that looks unimportant may bring in steady long-tail traffic.
- Switching off the old server too early. Keep redirects active until traffic to old URLs dies away, and then keep them anyway.
Who should be involved
A migration touches development, content and marketing. Make sure someone owns the redirect map, someone owns tracking, and someone has authority to delay the launch if testing finds problems. The cost of a short delay is tiny compared with the cost of losing search traffic for months. For a larger audit of your site before or after a move, our SEO audit guide is a good starting point.
FAQ
How long does it take for rankings to recover after a migration?
With good redirects, many sites see things settle within a few weeks. Larger sites and domain changes can take longer while search engines recrawl everything.
Should I use 301 or 302 redirects?
Use 301s for permanent moves. A 302 signals a temporary change, which is the wrong message for a migration.
Do I need to tell Google about a domain change?
Yes. Verify both domains in Search Console and use the Change of Address tool, along with 301 redirects on every URL.
Can I migrate without losing any traffic?
Some dip is common and usually temporary. Careful planning keeps it small and short.
Moving without losing ground
A migration should be a step forward, not a reset. We plan site moves around a full redirect map, staged testing and close monitoring after launch, so search visibility carries over. If you have a move coming up, see how we help businesses get found in search.
