Use Redirects Rather Than Orphaning an Old Page Before a Site Migration
When implementing a site migration, redirect old pages as soon as possible rather than removing internal links to them to try and encourage Google to drop them from the index.
Block Staging Sites From Being Crawled by Google
You should block Google from indexing your staging site as it can cause problems. You can block access based on Googlebot’s user agent, or using robots.txt.
Include Content That Matches Old Website Versions When Merging Sites
When merging multiple sites into one, John recommends including some content on the destination domain that matches the original domains that have been merged.
HSTS Isn’t Used as a Ranking Signal
HSTS doesn’t play any part in rankings. The main consideration from Google’s perspective is that it shouldn’t be added to a site during a time of fluctuation, like a migration. Make sure you only add it once rankings have settled and a migration has been completed successfully.
Use a Crawling Tool to Assess & Compare a Site Before & After a Migration
Before launching a site migration, John recommends using a crawling tool to get a full picture of your site’s status and signals (such as internal linking, canonicals etc.) both before and after the migration to compare.
A/B Testing During a Site Migration Can Delay Google Processing the Move
If you’re running large scale A/B testing during a site migration, this can confuse Google’s picture of your site and prevent it from running an algorithm to easily switch all of your URLs across to the new version.
Domain Migrations Take Longer if the New Domain Has Problematic History
Google can take longer to understand pages following a domain migration when the new domain has a problematic history e.g. spammy content and/or links.
Splitting or Merging Sites Can Take Months to Stabilise in Search
Splitting out or merging sites can be tricky for Google to understand. It can take time for Google to process these changes and it isn’t possible to predict what the final state might be in terms of rankings and traffic. A site migration may stabilise in search after a week or two and splitting or merging a site could take months to settle down.
Google Will Show Redirected Domains for Explicit Searches
If you are searching for the old domain name after a site migration then Google will try to show it to you even if it has recognised the new one. The best way to see if a migration has worked is to search for generic non-brand queries.