BigCommerce to Shopify Migration: Old URLs Returning 404 (How to Fix the Redirects)
BigCommerce and Shopify build URLs differently: BigCommerce category pages live at custom paths and blog posts at /blog/post-title/, while Shopify forces /collections/, /products/, and /blogs/news/post-title/. Product migration tools move the catalog but do not recreate your old BigCommerce 301 redirects, so every previously indexed URL that changed now returns a 404, and Google drops those pages from the index and lets their accumulated link equity evaporate. Shopify keeps no record of the old BigCommerce URLs and offers no automatic mapping, so there is no native undo: you must rebuild the redirect map yourself before the index erodes.
If you didn't already have a backup, those old values are gone — Shopify keeps no history.
The steps below recover what you can. To make the next time a 1-click undo instead of hours of CSV work: a daily snapshot of every SEO field. Free to monitor, no card — and SEO Vault only reads your store unless you click restore.
Stop the source: before you point your domain at Shopify (or immediately, if it is already switched), keep your BigCommerce store accessible and exportable. Its URL list and 301 redirect table are the master record of every address Google has indexed, and you need them to build the new map.
Recover the URL list: export your old URLs from BigCommerce (the 301 Redirects manager and the XML sitemap at /sitemap.xml), then cross-check against Google Search Console > Indexing > Pages and its Not found (404) report to capture every address Google actually crawled, plus the Wayback Machine for pages already gone.
Build redirects in Shopify: map each old BigCommerce URL to its new Shopify equivalent and create the 301s under Online Store > Navigation > URL Redirects. For large catalogs upload them in bulk via a redirect CSV (Shopify supports CSV import of redirects), then resubmit your Shopify sitemap in Search Console.
With redirects and handles fixed, install SEO Vault to snapshot every product and collection handle, meta, alt text, and tags daily. Handle changes are the silent killer: a future app or bulk edit that renames a handle breaks the URL and recreates the 404s you just fixed. SEO Vault flags the change, names the likely app, and lets you restore the original handle in one click.
Source: Shopify Help Center, URL redirects; Google Search Central, Site moves with URL changes
SEO Vault keeps a daily snapshot of every SEO field on your store — meta titles, descriptions, alt-text, tags, handles (products AND collections) — and emails you the moment something changes in bulk, with the likely app responsible. One click restores yesterday's state, just the SEO fields. Free to monitor and get alerted; $14/mo for 1-click restore.