Site migration without losing traffic: the sequence that works
Most migration losses are not caused by the redesign. They are caused by doing the steps in the wrong order, or discovering the mapping after launch instead of before it.
Key takeaways
- Build the URL inventory from crawl, Search Console and analytics together; each finds URLs the others miss.
- Redirect with a single 301 to the closest equivalent, never in bulk to the homepage.
- The most common catastrophic error is shipping the staging robots.txt disallow to production.
- Expect a two to six week dip; if traffic has not recovered by week eight, look for an unmapped class of URLs.
A site migration keeps its traffic when every old URL that had value resolves with a single 301 redirect to the closest equivalent new URL, and when that mapping is built and tested before launch rather than after it. Redesigns do not lose rankings. Broken mappings, redirect chains and quietly dropped content do.
Before you touch anything: the inventory
Build one spreadsheet containing every URL from three sources: your crawl, your Search Console data for the last sixteen months, and your analytics. The crawl finds what exists, Search Console finds what earns impressions, and analytics finds what earns revenue. Pages appear in one of these and not the others more often than teams expect, and a URL that no longer appears in your crawl but still receives search traffic is exactly the one that gets forgotten.
Add incoming links to the same sheet. A page with external links is carrying authority you cannot rebuild, so it must be redirected even if you intend to retire the content.
The mapping rules
- One hop. Old URL to new URL with a single 301. Chains dilute and slow crawling, and a chain that later loses its middle link breaks silently.
- Closest equivalent, never the homepage. Bulk-redirecting retired pages to the homepage is treated as a soft 404 and loses the value you were trying to preserve.
- If there is genuinely no equivalent, return 410. An honest gone status resolves faster than a redirect to something irrelevant.
- Preserve the URL where you can. Changing addresses for aesthetic reasons is risk without return.
Launch sequence
Test the redirect map on staging against the full inventory, not a sample. Confirm the new site's robots.txt does not carry the staging disallow, which is the single most common catastrophic migration error. Verify canonical tags, hreflang pairs and structured data on the new templates. Then launch, and immediately re-crawl the old URL list in production to confirm every one resolves as intended.
Submit the new sitemap, and keep a sitemap of the old URLs available for a few weeks so the redirects are discovered quickly. Do not remove the old property from Search Console; you need both to watch the handover.
The first eight weeks
Expect a dip. A migration of any size usually shows a decline for two to six weeks while the index reprocesses, and recovery to previous levels is a reasonable expectation rather than an immediate one. Watch the index coverage report for a rising count of crawled but not indexed pages, watch for spikes in 404s, and compare impressions rather than clicks in the first fortnight because click data is noisier.
If traffic has not recovered by week eight, the cause is almost always in the inventory: a class of URLs that was never mapped. Go back to the spreadsheet rather than to the content.
Redesigns do not lose rankings. Unmapped URLs do.
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