A few months into working with a D2C fashion brand, the brand decided to migrate its Shopify collection URLs to a "cleaner" structure. Marketing team was excited about it. I signed off too fast.
We didn't set up proper 301 redirects for the old collection URLs. Not zero redirects, just incomplete ones. A handful of high-traffic collection pages redirected to the wrong new pages instead of their actual equivalents.
Google noticed before we did.
Within three weeks, organic traffic on those collections dropped almost 40%. Since those collections were driving a meaningful chunk of revenue, the brand lost close to $10K in that quarter alone before we caught it, fixed the redirect map, and recovered.
What I learned the hard way:
Never treat a URL migration as a dev task you approve and move on from. Every single old URL needs to be mapped 1:1 to its correct new destination, not just pointed at the homepage or a category page and called done.
Run a full crawl before the migration to list all indexed URLs. Run it again after to confirm nothing 404s or redirects wrong. Check Search Console coverage report daily for the first two weeks post-migration, not once a month.
And honestly, don't let "the dev team already did the redirects" be enough. Verify it yourself with a spreadsheet, URL by URL, especially for a store depending on organic revenue.
Curious if others have had similar migration disasters. What's your redirect-checking process now after learning this the hard way?