The CMS Migration Playbook: Move Content Without Losing Traffic

CMS migrations are high-stakes projects. When they go well, you get a faster, more flexible platform without missing a beat in search rankings or user experience. When they go poorly, you lose organic traffic, break user journeys, and spend months trying to recover rankings that took years to build.

The difference between these outcomes almost never comes down to the new CMS itself. It comes down to planning, specifically how thoroughly you inventory your content, how carefully you map URLs, and how rigorously you test before and after launch.

This playbook gives you a repeatable process for migrating content between platforms without sacrificing the SEO equity and user experience you have built.

Before You Start: Define Success

Every migration needs clear success criteria established before the project begins. Without them, you will not know whether the migration went well or just felt okay.

Set measurable targets for:

• Organic traffic: What percentage of pre-migration traffic do you expect to retain at 30, 60, and 90 days post-launch?
• Indexed pages: How many pages should be indexed in the new site versus the old one?
• Core Web Vitals: What performance thresholds must the new platform meet?
• Conversion rates: Are you maintaining or improving key conversion metrics?
• Crawl errors: What is the acceptable number of 404s or redirect errors after launch?

Document these targets and share them with every stakeholder. They will guide every decision during the migration.

Phase 1: Content Inventory and Audit

You cannot migrate what you do not know you have. The first phase is building a complete picture of your current site.

Crawl the Existing Site

Run a comprehensive crawl that captures:

• Every URL on the site (including pages not in the navigation)
• Page titles, meta descriptions, and H1 tags
• HTTP status codes
• Internal link relationships (which pages link to which)
• Canonical tags and hreflang annotations
• Structured data markup
• Image URLs and alt text

Layer in Performance Data

For every URL, pull in:

• GA4 data: Sessions, engaged sessions, conversions over the last 12 months
• Google Search Console data: Impressions, clicks, average position, and the queries driving traffic
• Backlink data: Pages with external links pointing to them (these are your highest-risk URLs)

Decide What Migrates

Not everything deserves to move to the new platform. Use your crawl and performance data to categorize each page:

• Migrate as-is: High-performing, current content that moves over unchanged.
• Migrate and improve: Content worth keeping but needing updates during the transition.
• Consolidate: Multiple pages covering the same topic that should become one stronger page.
• Retire: Outdated, thin, or irrelevant content that gets redirected to a relevant alternative or returns a 410.

This is the most important decision-making step in the entire process. Rushing it is the single most common cause of migration failures.

Phase 2: URL Mapping and Redirect Strategy

URL mapping is where migrations succeed or fail. Every old URL must resolve to a destination on the new site or return an intentional status code.

Build Your URL Map

Create a spreadsheet with these columns:

Redirect Rules

Follow these principles to preserve SEO equity:

1. Use 301 redirects for permanent moves. Never use 302s for content that has permanently changed location.
2. Redirect to the most relevant page, not the homepage. Mass-redirecting to the homepage signals to search engines that the redirects are not meaningful.
3. Avoid redirect chains. If page A already redirects to page B, and page B is moving to page C, update the redirect so A goes directly to C.
4. Preserve query parameters if your old site used them for tracking or filtering.
5. Handle trailing slashes consistently. Pick one convention and redirect the other.
6. Map your highest-value pages first. Sort by traffic, backlinks, and conversion value, and ensure the top 20% of pages get manual attention.

Pattern-Based Redirects

For large sites, you will need regex-based redirect rules to handle URL pattern changes at scale. For example:

• /blog/YYYY/MM/slug becomes /insights/slug
• /products/category/item becomes /solutions/category/item

Test every pattern against your full URL list to catch edge cases before launch.

Phase 3: Content Preparation

With your inventory complete and URLs mapped, prepare the content for the new platform.

Template Mapping

Document how content types map between the old and new CMS:

• Which fields exist in both systems?
• Which fields need to be created in the new CMS?
• What happens to content that does not fit the new templates?

Metadata Migration

Ensure these elements transfer for every page:

• Page titles
• Meta descriptions
• Open Graph and Twitter Card tags
• Canonical URLs (updated to the new domain/path structure)
• Structured data / JSON-LD
• Hreflang tags (for multilingual sites)

Asset Migration

Do not forget non-page content:

• Images and their alt text
• PDFs, whitepapers, and downloadable files
• Videos and embedded media
• Internal links within content bodies (these need to be updated to new URLs)

Phase 4: Pre-Launch Testing

Never launch without testing. The cost of finding problems before launch is a fraction of fixing them after.

Technical Checks

• Crawl the staging site and compare the page count against your inventory. Every page in your migration list should be present.
• Validate redirects by testing every rule against a sample of old URLs. Automated tools can test hundreds of redirects in seconds.
• Check for redirect chains and loops that could slow page loads or confuse search engines.
• Verify canonical tags point to the correct new URLs, not the old ones.
• Test structured data with Google's Rich Results Test on key page templates.
• Run Core Web Vitals tests on the staging site to catch performance regressions.

Content Checks

• Spot-check content on at least 10% of migrated pages to verify formatting, images, and links rendered correctly.
• Verify internal links within content bodies point to new URLs, not old ones that will redirect.
• Check navigation to ensure all menu items, footer links, and breadcrumbs work correctly.
• Test forms and interactive elements that may behave differently on the new platform.

SEO Checks

• Robots.txt: Ensure the new site is not blocking crawlers from critical sections.
• XML sitemap: Generate and validate a new sitemap with all migrated URLs.
• Meta robots tags: Verify no pages are accidentally set to noindex.
• Analytics tracking: Confirm GA4 and any other tracking scripts fire correctly on every page template.

Phase 5: Launch Day

When you are confident in your testing, execute the launch:

1. Deploy the new site and activate redirect rules simultaneously.
2. Submit the new XML sitemap to Google Search Console immediately.
3. Request indexing for your most important pages through Search Console.
4. Monitor server logs for unexpected 404s or 500 errors in real time.
5. Test a sample of redirects on the live site to confirm they are working.
6. Verify analytics tracking is recording data on the new site.

Phase 6: Post-Migration Monitoring

The migration is not done on launch day. The first 90 days are critical for catching and fixing issues.

Week 1

• Monitor Google Search Console for crawl errors daily.
• Check for spikes in 404 errors or soft 404s.
• Verify Google is discovering and indexing new URLs.
• Watch organic traffic for any sudden drops.

Weeks 2 to 4

• Compare indexed page counts (old vs. new) in Search Console.
• Review search ranking changes for your top 50 keywords.
• Check that old URLs are being removed from the index as new ones are added.
• Fix any redirect issues that surface from real user traffic.

Months 2 to 3

• Compare organic traffic against your pre-migration baseline.
• Analyze engagement metrics (bounce rate, session duration) for migrated content.
• Review Core Web Vitals data as Google collects field data from the new site.
• Document lessons learned for future migrations.

Common Post-Migration Issues

• Traffic drop in week one: Normal. Google needs time to process redirects and re-evaluate the new URLs. Significant drops lasting beyond 4 to 6 weeks indicate a problem.
• Orphan pages on the new site: Pages that exist but have no internal links pointing to them. Run a crawl to identify and fix these.
• Mixed content or broken images: Assets still referencing old URLs. Update internal links in content bodies.
• Duplicate content: Both old and new URLs indexed simultaneously. Verify redirects and canonical tags.

The Migration Safety Net

Migrations fail when teams lack visibility into their existing site. When you do not know exactly how many pages you have, which ones drive traffic, and how they link together, every decision is a guess.

Evergreen gives you that visibility before, during, and after a migration. Crawl your current site to build a complete content inventory, overlay GA4 and Google Search Console data to identify your highest-value pages, and use the visual sitemap to understand the structural relationships you need to preserve. After launch, crawl the new site to verify page counts, catch orphan pages, and confirm that your redirect strategy is working.

A CMS migration does not have to be a traffic gamble. With the right data and a methodical process, you can move platforms with confidence.