Website migrations are one of the riskiest operations in digital marketing. Whether you're moving to a new domain, switching CMS platforms, restructuring your URL hierarchy, or redesigning your entire site, the outcome is often the same: broken links everywhere. A single overlooked redirect can wipe out months of SEO progress, tank your organic traffic, and frustrate loyal visitors who suddenly can't find the content they need.

In this comprehensive guide, we'll walk through exactly how to check links after migration, why site migration broken links are so dangerous, and how to build a bulletproof process that protects your rankings throughout the transition.

Why website migrations create so many broken links

A website migration involves changing something fundamental about how your site is accessed — its domain, URL structure, technology stack, or content architecture. Each of these changes has the potential to break every internal and external link pointing to your old URLs.

Here are the most common migration scenarios and why they generate broken links:

Domain changes

Moving from oldsite.com to newsite.com means every single URL on your site changes. If you don't set up comprehensive 301 redirects from the old domain to the new one, every inbound link, bookmark, and search engine index entry becomes a dead end. Even with redirects in place, you need to update all internal links to point directly to the new domain to avoid unnecessary redirect chains.

CMS platform migrations

Switching from WordPress to Shopify, from Drupal to a headless CMS, or from a custom system to any new platform almost always changes your URL structure. WordPress might use /2026/03/post-title/ while your new platform uses /blog/post-title. Every page on your site could end up with a different URL, creating hundreds or thousands of broken links overnight.

URL restructuring

Even without changing platforms, reorganizing your site architecture — flattening deep hierarchies, renaming categories, or consolidating content — changes URLs. A page at /products/electronics/phones/iphone moving to /phones/iphone breaks every existing link to the old path.

HTTPS migrations

Migrating from HTTP to HTTPS changes every URL on your site. While modern browsers handle this gracefully, search engines treat http:// and https:// as different URLs. Without proper redirects, you'll have duplicate content issues and broken links from external sites still pointing to your HTTP URLs.

The real cost of broken links after a site migration

The damage from post-migration broken links goes far beyond a few 404 pages. Here's what's actually at stake:

Organic traffic drops of 20-60% — it's common to see significant traffic losses in the weeks following a poorly executed migration. Some sites never fully recover.
Lost link equity — every external backlink pointing to a broken URL is wasted authority. If you've spent years building links, a botched migration can erase that investment. Learn more about why broken links hurt your SEO.
Crawl budget waste — Googlebot spends time crawling 404 pages instead of indexing your actual content, slowing down the re-indexing of your new site structure.
User frustration and lost revenue — visitors arriving from old bookmarks, email links, or social media posts hit dead pages. For e-commerce sites, every broken product page is a lost sale.
Damaged brand reputation — a site full of broken links looks abandoned and untrustworthy.

Pre-migration: Building your link inventory

The best time to prevent broken links is before the migration starts. Here's how to build a comprehensive link inventory that will serve as your migration checklist.

Crawl your existing site thoroughly

Use Broken Link Scan to crawl your current site and create a complete map of every URL. This gives you a baseline of all pages that need to be redirected. Export the full list of URLs — you'll need this as your redirect mapping source.

Collect your backlink profile

Use Google Search Console, Ahrefs, or Semrush to export every external URL that links to your site. These are the URLs that absolutely must be redirected because you can't update them — they live on other people's websites. Prioritize pages with the most backlinks, as these carry the most link equity.

Document your top-performing pages

Pull your top 100 pages by organic traffic from Google Analytics. These are the pages where broken links will hurt the most. Double-check that each one has a correct redirect mapped to equivalent content on the new site.

Create a complete redirect map

Build a spreadsheet mapping every old URL to its new equivalent. This is the single most important document in your migration. The format is simple:

Old URL                          → New URL
/products/widget-a               → /shop/widget-a
/blog/2025/01/my-post            → /blog/my-post
/about/team                      → /company/team

For pages that are being removed entirely, redirect them to the closest relevant page — never to the homepage as a catch-all, as Google treats that as a soft 404.

During migration: Implementing redirects correctly

With your redirect map ready, it's time to implement. The technical details matter enormously here.

Use 301 redirects, not 302

A 301 redirect tells search engines the move is permanent and they should transfer link equity to the new URL. A 302 redirect signals a temporary move and doesn't pass full link equity. Always use 301 for migrations.

Avoid redirect chains

If page A already redirected to page B, and now page B is moving to page C, update the redirect so A goes directly to C. Chains of three or more redirects cause search engines to drop link equity at each hop, and after about five hops, Googlebot may stop following entirely.

Handle URL patterns, not just individual pages

Instead of writing thousands of individual redirects, use pattern-based rules where possible. For example, in Nginx:

rewrite ^/blog/(\d4)/(\d2)/(.*)$ /blog/$3 permanent;

This single rule redirects all date-based blog URLs to the new flat structure. It's more maintainable and less error-prone than individual entries.

Don't forget non-HTML resources

PDFs, images, downloadable files, and API endpoints all have URLs too. If other sites link to your PDF whitepapers or product images, those URLs need redirects as well. Broken images are particularly visible to users — read our guide on how broken images affect SEO.

Post-migration: How to check links after migration

The migration is live. Now comes the critical validation phase. Here's a systematic approach to finding and fixing every broken link on your migrated site.

Step 1: Run a full site crawl immediately

As soon as the new site is live, run a complete crawl with Broken Link Scan. This will identify:

Internal links pointing to old URLs that weren't updated
Broken images and media files that didn't migrate correctly
External links that may have changed since your pre-migration inventory
Redirect chains and loops that need to be simplified

Step 2: Validate your redirect map

Take the redirect map you created before migration and test every single entry. Automated tools can help, but spot-check the most important pages manually. Verify that:

Each old URL returns a 301 (not a 302 or 404)
Each redirect lands on the correct destination page
There are no redirect chains longer than one hop
The destination page loads correctly with all resources

Step 3: Monitor Google Search Console

Check the Coverage report in Google Search Console daily for the first two weeks after migration. Watch for:

Spikes in 404 errors — these are URLs Google is trying to crawl that no longer exist
"Crawled - currently not indexed" pages — your new URLs may take time to enter the index
Redirect errors — Search Console will flag redirect chains and loops
Mobile usability issues — the new site may have different mobile behavior

Step 4: Check your analytics for traffic anomalies

Compare organic traffic to the pre-migration baseline. Some fluctuation is normal in the first week, but if traffic drops more than 15-20% after two weeks, you likely have redirect gaps. Look at the specific pages losing traffic to identify which redirects are missing or broken.

Step 5: Test external backlinks

Take the backlink inventory you built before migration and test the top 50-100 URLs. Click through each one to verify it redirects correctly to the new equivalent page. These are your most valuable links — a single broken backlink from a high-authority site could cost you more ranking power than dozens of minor internal fixes.

Common migration mistakes that cause broken links

After helping thousands of websites with link checking, these are the mistakes we see most often:

Forgetting trailing slashes

Your old site might have used /about/ (with trailing slash) while your new site uses /about (without). These are technically different URLs. Make sure your server configuration handles both variants, or you'll miss redirects for all the URLs that were indexed with a trailing slash.

Case sensitivity issues

Some servers treat /About and /about as different URLs. If your old site had mixed-case URLs in its backlink profile, make sure your redirect rules are case-insensitive, or add explicit rules for common variations.

Missing query parameters

URLs with query strings like /products?category=shoes may not match your redirect rules if those rules only handle the path. UTM parameters, pagination parameters, and filter parameters all need consideration.

Not updating internal links

A redirect catches the broken link, but it's not a permanent solution. Update all internal links in your content, navigation, sitemaps, and templates to point directly to the new URLs. This eliminates unnecessary server-side redirects and passes link equity more efficiently.

Ignoring embedded content

Images, CSS files, JavaScript files, and fonts all have URLs. If your migration changes the structure of your static assets folder, you can end up with pages that load but look broken because the styles and images fail to load.

Setting up ongoing monitoring after migration

The first scan after migration isn't enough. New broken links will surface over the following weeks as search engines and users access URLs you didn't anticipate. Set up automated monitoring to catch issues early.

Broken Link Scan's monitoring plans can automatically re-scan your site on a regular schedule and alert you when new broken links appear. This is particularly valuable in the first three months after a migration, when lingering issues are most likely to surface.

You should also keep an eye on these sources of ongoing breakage:

Old email campaigns — marketing emails sent before the migration contain old URLs that may be clicked months later.
Social media posts — old tweets, Facebook posts, and LinkedIn articles with your old URLs will keep generating traffic indefinitely.
Third-party directories — business listings, review sites, and directories may link to old URLs that need redirects.
Print materials — if old URLs were printed on business cards, brochures, or packaging, those links need to work.

Migration checklist: Prevent broken links step by step

Here's a condensed checklist you can follow for any website migration:

Pre-migration: Crawl the old site and export all URLs
Pre-migration: Export your backlink profile from Search Console
Pre-migration: Build a complete redirect map (old URL → new URL)
Pre-migration: Document your top 100 pages by organic traffic
During migration: Implement 301 redirects from the redirect map
During migration: Update all internal links to new URLs
During migration: Update XML sitemap with new URLs
Post-migration: Crawl the new site with Broken Link Scan
Post-migration: Validate redirect map against live site
Post-migration: Monitor Search Console for 404 spikes
Post-migration: Set up automated broken link monitoring
Post-migration: Compare organic traffic weekly for 3 months

Conclusion

Broken links after a website migration aren't a matter of if, but how many. The difference between a smooth migration and a traffic disaster comes down to preparation, thorough redirect mapping, and rigorous post-migration validation. Start by scanning your site for free — whether you're planning a migration or recovering from one, knowing exactly where your broken links are is the first step to fixing them.

Broken Links After Website Migration: How to Find and Fix Every Dead URL