Technical SEO guide

SEO Site Migration: URLs, Redirects, Canonicals and Hreflang

Treat a URL move as a controlled search transition. Every valuable old URL needs one verified outcome: equivalent destination, relevant consolidation, or intentional removal.

Published: Jul 15, 2026
Updated: Jul 15, 2026
Reading time: 15 min read

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A migration is not one event. Separate an identity move, such as a domain or path change, from an infrastructure move, such as a CDN, DNS, or hosting change with the same public URLs. Google recommends changing one major variable at a time where possible.

Overview

Outcome

Build a tested URL map and launch process that keeps redirects, canonicals, hreflang, sitemaps, rendering, and operational delivery signals aligned.

Decide whether public URLs are changing

Migration	URL changes?	Core controls
Domain, subdomain, protocol, or path	Yes	URL map, permanent redirects, canonical and hreflang updates, new sitemap
CMS redesign with retained URLs	Ideally no	Rendering, metadata, content, and internal-link parity
CDN, hosting, or DNS switch	No	TLS, bot access, headers, cache, logs, and crawler-delivery parity
Mixed move	Some	Split into controlled workstreams where possible

Do not use Search Console Change of Address for a CDN or hosting move that retains public URLs. That is an infrastructure migration, not a redirect project.

Build the URL map before redirect rules

Source old URLs from sitemaps, CMS data, logs, analytics, internal links, Search Console, feeds, and strategic landing pages. For each old URL, choose an exact equivalent, relevant consolidation, or intentional 404/410. Do not redirect unrelated discontinued products or content to the home page.

SEO migration control path

Inventory
Collect legacy URLs and business priority.
Map
Set one destination or intentional removal per URL.
Implement
Deploy server-side redirects and new annotations together.
Validate
Check HTTP, rendered HTML, crawler paths, and search signals.

One approved URL map drives redirect rules, canonical URLs, hreflang clusters, sitemaps, and launch validation.

Use server-side 301 or 308 for permanent moves. For ordinary crawled GET URLs, Google treats both as strong permanent signals; 308 preserves request method and body, while a client may change a POST after 301. Redirect directly to the final destination and avoid chains and loops.

Representative URL-map validation

old=https://old.example.com/fr/shoes/red
status=301 final=https://www.example.com/fr/chaussures/rouges
final_status=200 canonical=self hreflang_cluster=reciprocal
rendered_title=present sitemap=new-canonical-only result=pass

Keep canonical, hreflang, and sitemap signals consistent

Every new indexable destination should self-canonicalise. Redirects and canonical annotations are strong signals; sitemap inclusion is weaker. They must identify the same preferred URL. Rebuild each hreflang cluster with fully qualified new URLs, self-reference, reciprocal return links, and same-language canonicals. Submit a sitemap of canonical 200 URLs only and update internal links instead of depending on redirects indefinitely.

Treat rendering and infrastructure as release gates

Validate raw HTTP response, rendered HTML, browser output, canonical, robots directives, sitemap, structured data, and essential JavaScript/CSS access. A 200 response is not proof of indexability or correct rendering. For a no-URL-change CDN move, test DNS, TLS, host headers, cache key and Vary, bot WAF rules, redirects, image delivery, and purge behaviour from multiple regions.

Troubleshooting

Migration mistakes that create search loss

Combining a domain move with redesign, taxonomy, CMS, locale, and rendering changes without a phased plan.
Using temporary redirects for permanent moves, or redirecting every removed URL to the homepage.
Leaving noindex, password protection, or development robots rules in production.
Sending conflicting redirect, canonical, sitemap, internal-link, and hreflang signals.

Authoritative references

Make the next migration observable and reversible

Optimi can help connect technical SEO, edge delivery, logs, and rollback controls before a URL or infrastructure move goes live.

Review a site migration