Website Migration SEO

Website migrations (domain changes, platform changes, or major site restructures) are among the highest-risk SEO events. A poorly executed migration can cause significant traffic and revenue loss.

Learning Focus

After this lesson you can assess migration risk, map URLs, plan redirects, validate staging, monitor launches, and plan rollbacks.

This lesson covers the eight migration areas (leaves 11.2.1–11.2.8): migration risk assessment, URL mapping, redirect planning, staging crawl, analytics and tracking validation, launch monitoring, post-migration recovery, and rollback planning.

Migration Risk Assessment

Assess the risk level of the planned migration.

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Risk factors:

Factor	Higher Risk	Lower Risk
URL changes	All URLs change	Same URLs, same structure
Platform change	Different CMS	Same CMS, different version
Content changes	Content restructured or reduced	Content preserved
Domain change	New domain	Same domain
Site architecture	Information architecture changes	Same structure
Redirect complexity	Thousands of redirects needed	Few redirects needed

Risk levels:

Level	Characteristics	QA Required
Low	Same platform, same URLs, minor design changes	Standard QA
Medium	New platform, same URL structure, content preserved	Extended QA, staged rollout
High	New domain, new URLs, new platform	Full migration process, rollback plan

URL Mapping

Core Concept

Map every existing URL to its new URL.

URL mapping requirements:

Requirement	Description
Every current URL	Every page that has traffic, links, or indexation must be mapped
1:1 mapping where possible	Each old URL maps to the most relevant new URL
Content-based	The new URL should have equivalent or better content
No generic redirects	Avoid catch-all redirects to the homepage
External link preservation	URLs with external backlinks should have dedicated redirects

URL mapping process:

1. Export all current URLs from crawl, sitemaps, GSC (indexed pages).
2. For each URL, determine the appropriate new URL or handling (redirect, 404, consolidate).
3. Document the mapping in a spreadsheet.
4. Validate the mapping for accuracy.

Redirect Planning

Plan redirect implementation.

Redirect requirements:

Requirement	Implementation
301 for permanent moves	All URL changes use 301 (not 302)
1:1 redirects	Avoid redirect chains
Wildcard redirects	Only for pattern-based changes (e.g., /oldblog/ → /blog/)
No redirect chains	Maximum 1 redirect hop
Redirect validation	Test every redirect before launch

Staging Crawl

Crawl the staging environment to verify configurations before launch.

Staging crawl checks:

Check	Method
All URLs return 200	Crawl staging
Meta tags present	Crawl check
Canonical tags correct	Crawl check
Schema validates	Rich Results Test on samples
Mobile rendering passes	Lighthouse (mobile audit)
Page speed passes	Lighthouse
No noindex on pages that should be indexed	Crawl check
Internal links work	Crawl check

Analytics and Tracking Validation

Verify that analytics, tracking, and conversion measurement work after migration.

Validation checks:

Check	Method
GA4 tracking code fires	Real-time report
GSC property verified	GSC verification
Conversion events fire	GA4 debug view
UTM parameters work	Test URLs
CRM integration	Test form submissions
Heatmap/session recording	Verify on new pages

Launch Monitoring

Monitor the site closely immediately after launch.

Post-launch monitoring (24-72 hours):

Check	Frequency	Action if Issue Found
GSC crawl errors	Every 2-4 hours	Fix errors immediately
Index coverage	Every 4 hours	Check for unexpected drops
Organic traffic	Compare to pre-launch	Investigate drops
Server errors (5xx)	Real-time	Fix immediately
Redirect validation	Spot-check 50 redirects	Fix incorrect redirects
Search appearance	Manual brand search	Check for issues

Post-Migration Recovery

Monitor and optimize the site in the weeks after migration.

Recovery monitoring (first 4-8 weeks):

Metric	Expected Pattern	Action
Organic traffic	May drop 10-30% initially, recover over 4-8 weeks	If drop exceeds 40%, investigate
Indexed pages	Should return to pre-migration count within 4 weeks	If not, check sitemaps, crawl
Rankings	May fluctuate, should stabilize by week 8	If not, review content quality
Core Web Vitals	Should be at least at pre-migration level	If worse, optimize

Rollback Planning

Plan for the possibility of rolling back the migration.

Rollback criteria:

Criterion	Decision
Traffic drop > 50% after 1 week	Consider rollback
Critical SEO configuration not working	Rollback until fixed
Revenue impact exceeds threshold	Rollback or staged restore
Major technical issues unresolved after 24 hours	Rollback

Rollback plan components:

1. How to restore old site (backup, database, DNS).
2. How to preserve any new content created on the new site.
3. Communication plan for stakeholders.
4. Timeline for reattempting migration.

What's Next

• Algorithm & Policy Risk Management
• Module Overview

References

• Google Search Central: Site moves
• Google Search Central: Site move checklist
• Google Search Central: Redirects