SEO During Website Migration: Preventing Traffic Loss in Large Site Moves

Introduction

Website migrations are among the highest-risk technical SEO projects.

A migration may involve:

• Domain changes
• URL restructuring
• CMS changes
• HTTP to HTTPS
• Platform migration
• Website redesign
• International restructuring

Even small mistakes can cause significant traffic losses.

Build a URL Mapping System

Before launching, create a mapping table:

Old URL → New URL → Redirect → Status → Validation

Every valuable old URL should have a planned destination.

Redirect Strategy

Permanent redirects should point users and search engines toward the most relevant new page.

Avoid redirecting thousands of unrelated URLs to the homepage.

Pre-Launch Testing

Test:

• Canonical tags
• Robots directives
• XML sitemaps
• Internal links
• Status codes
• Structured data
• Mobile versions
• Metadata

Post-Launch Monitoring

After migration, monitor:

• Organic clicks
• Impressions
• Indexing
• Crawl errors
• Redirect chains
• 404 responses
• Rankings
• Conversions

Google’s 2026 documentation has continued updating site-move guidance, including handling domain variants during migrations.