What Types of Website Migrations Affect SEO?
Website migrations affect SEO when Google sees different URLs, different content or different technical signals than before. The greater the change, the greater the risk of temporary or permanent traffic loss.
These migrations always require SEO control.
| Migration type | SEO risk | Main control |
|---|---|---|
| Domain change | Google needs to process all authority to a new domain | Complete 301 redirect folder and address change in Search Console |
| New URL structure | Old rankings disappear when URLs do not redirect correctly | One-to-one redirects from old to the most relevant new URL |
| CMS migration | Templates, metadata, schema and indexation settings change | Pre-live crawl, metadata check and robots check |
| Redesign | Content, headings and internal links are often unintentionally weakened | Compare content parity and internal link structure |
| HTTPS or technical rebuild | Mixed redirects, canonical errors or crawl problems arise | Check Canonical tags, status codes and sitemap |
Which SEO checklist do you use before migration?
Before the migration, you use a checklist that maps all existing SEO value. Without a baseline assessment, you will not know after go-live what was lost or which page has priority.
- Export all indexable URLs from crawling software, sitemap and Google Search Console.
- Highlight pages with traffic, backlinks, conversions and rankings.
- Create a redirect map from each old URL to the appropriate new URL.
- Controleer of titels, meta descriptions, H1's en hoofdcontent behouden blijven.
- Test robots.txt, canonical tags, hreflang and structured data on staging.
- Crawl the staging website and resolve 404s, redirect chains, and noindex errors.
- Plan go-live at a quiet time, so that errors are immediately followed up.
Why are 301 redirects so important?
301-redirects are important because they permanently redirect Google and users from an old URL to the correct new URL. Without a correct redirect, the new page loses the built-up signals from the old page and often results in a 404 error.
Google describes the approach in its documentation about site moves with URL changes. The best redirect is not always to the homepage, but to the most relevant replacement page.
What do you check on the day of go-live?
On the day of go-live, check status codes, redirects, indexability, tracking, canonical tags, sitemap and main landing pages. The first hours often determine how quickly errors are found.
Use this go-live check.
- Main old URLs give a 301 to the correct new URL
- Most important new URLs give status code 200
- Robots.txt does not block important sections
- Canonical tags point to the correct new URLs
- New XML sitemap is available and submitted
- Analytics, conversions and forms work
- Internal links do not point en masse to old URLs
How do you monitor rankings after a migration?
After a migration, you monitor indexing, 404 errors, redirect errors, organic traffic, rankings, conversions and crawl statistics. A temporary dip is normal, but technical errors must be resolved quickly.
Use Google Search Console for indexing, sitemaps and error reporting. Compare traffic by URL group, not just at the aggregate level. This way you can see which template, category or pages are left behind.
In practice
A temporary decrease after a migration is normal. Panic actions are more dangerous than the dip itself. First you check redirects, indexability and content parity. Only then do you decide whether additional optimization is necessary. Anyone who immediately re-adjusts structure and content often makes the cause more unclear.
What mistakes cause ranking loss?
Ranking loss is usually caused by missing redirects, changed content, broken internal links, noindex errors, canonical errors or a robots.txt that blocks too much. A redesign that hides or removes important text can also affect positions.
Prevent this with a SEO audit before migration and a technical crawl immediately after go-live. Website migration is a part of technical SEO and affects your entire what is SEO.