Five steps decide it: a complete URL inventory, a mapping of every old URL to a target with matching content, a check of all redirects against staging, a measurement plan for tracking, and a review of indexing and order numbers after go-live. If one is missing, the damage shows up weeks later in Search Console.
We build the URL inventory from the sitemap, Search Console, analytics, server logs and our own crawl. That surfaces pages which are only linked from outside and have long disappeared from the Shopware backend. Every URL gets a permanent redirect to the page that carries the same content, including the language versions. We do not set catch-all redirects to the homepage. Kanela, a migration from Prestashop, shows how large such a list can get: 147,753 SEO redirects. Titles, descriptions, headings and structured data move as well. The page on Shopify SEO describes the work after launch.
Tracking gets lost in migrations because it grew inside plugins and templates over years and was never written down. Before the move we record which events reach Google Analytics, Google Ads and Meta today, and rebuild them in Shopify through Customer Events and consent management. Test orders run through every payment method before go-live. After go-live we reconcile measured purchases with the orders in Shopify. At Olakala, server-side tracking on Shopify Plus recorded 30% more sessions. The page on tracking setups explains the structure.
No platform change comes with a guarantee of unchanged rankings. Google evaluates a new store again, and positions move in the first weeks. We are responsible for every old URL reaching a target and for fixing the 404 errors that appear after launch.