Direct answer

Shopify migrations usually fail at the connections between systems, not at copying visible pages. Product variants lose identifiers, customer passwords cannot be transferred through ordinary CSV migration, historical orders fail to link, redirects are incomplete, subscriptions and gift balances diverge, fulfilment workflows stop, analytics reset and finance totals no longer reconcile. Prevent this with an authoritative data map, repeated trial migrations, URL-level redirect mapping, end-to-end order testing and a rehearsed cutover with rollback criteria.

Treat migration as an operating-system change, not a theme project. The launch gate should require evidence that customers can discover products, sign in or recover access, pay, receive accurate communications, obtain fulfilment and refunds, and that finance can reconcile the result.

Define migration scope before selecting tools

Inventory the source platform, storefront, product information, ERP, warehouse, payments, subscriptions, loyalty, reviews, search, tax, customer service, analytics, marketing feeds and domains. For every object, record source of truth, destination, identifier, volume, history required, transformation, owner and acceptance rule.

Classify data as migrate, archive, rebuild or retire. Not every obsolete page, customer or application deserves movement. Preserve legal and accounting records according to policy even when they do not need to be active in Shopify.

What breaks in product data

CSV and app imports often flatten rich source models. Variant options can exceed destination assumptions; SKUs and barcodes can be missing or duplicated; bundles, subscriptions and customizations may not map; image order and alt text can change; category and metafield types can be lost. Collection rules may produce unexpected membership.

Build a canonical product model before import. Validate handle, title, description, vendor, product type, category, status, tags, option names, variant identifiers, prices, compare-at prices, cost, inventory policy, weight, harmonized-system code, origin, tax category, images, SEO fields and required metafields. Quarantine rows that fail rather than silently creating partial products.

How to fix product migration

Import a representative subset containing the hardest products, not the cleanest. Compare source and Shopify counts by product, variant and image; sample field-level values; and test storefront selection and cart behavior. Keep an immutable source export and a transformation log.

Products should normally be imported before customers and historical orders so later records can link correctly, matching Shopify’s migration guidance. Freeze identifier changes after the final mapping begins or maintain a delta process.

What breaks in inventory

Inventory becomes inaccurate when the source, warehouse and Shopify all accept writes during cutover. Location identifiers may not map, reserved stock may be omitted and bundles may double-count components. An import that was correct at extraction can be wrong by launch.

Choose the launch source of truth and define a transaction freeze or delta synchronization. Map every source location to Shopify, reconcile available, committed, incoming and damaged quantities, then place test orders and verify decrement, cancellation, fulfilment and return. Record the exact timestamp of the final inventory load.

What breaks in customer accounts

Customer records can migrate, but ordinary password hashes generally cannot. Shopify states that passwords encrypted outside Shopify cannot be imported through customer CSV; customers need an invitation or account recovery path. Marketing consent, addresses, tags and metafields also require careful mapping.

Design the account transition as a customer campaign. Explain what changes, provide a low-friction activation or password-reset journey, protect against phishing confusion and train support. Test duplicate emails, phone-only customers, guest orders, international addresses and suppressed contacts. Do not mark imported users as opted in without valid consent evidence.

What breaks in historical orders

Historical order imports can lose discounts, tax lines, fulfilment state, returns, payment method, currency or links to products and customers. Imported orders may trigger operational notifications if configuration is not controlled. They can also distort reporting if migration date and original order date are confused.

Decide why history is needed: customer self-service, support, analytics, finance or retention. Shopify documents apps and APIs as options for historical orders and warns about notification effects. Disable or isolate downstream automation during tests. Reconcile order counts and financial components by period and currency.

What breaks in subscriptions, loyalty and gift value

Recurring-payment tokens, subscription contracts, loyalty balances, gift cards and store credits are not ordinary product or customer fields. Provider portability, customer authorization and platform support determine the path. A naive import can create value twice or strand valid balances.

Run a separate migration workstream for each liability. Reconcile opening and closing totals, retain customer-level evidence, define redemption behavior and test renewals, skips, cancellations, refunds and failed payments. Communicate material changes before cutover.

What breaks in SEO

Search performance drops when old URLs return 404, many pages redirect to the homepage, canonicals point incorrectly, metadata disappears, internal links retain source paths, structured data changes or robots directives block the new site. Domain changes and market subfolders multiply the risk.

Crawl the source before migration and export every indexable URL, status, canonical, title, H1, metadata, structured-data type, internal links, organic clicks, impressions and backlinks. Build a one-to-one redirect map to the closest genuine equivalent. Preserve high-performing URLs when possible.

Redirect implementation

Shopify supports URL redirects for broken paths and bulk workflows, with reserved paths and limits documented in the Help Center. Import and test redirects in a staging or post-launch environment. Confirm a single permanent hop, correct market behavior and no redirect loops.

Do not redirect removed products to the homepage. Use an equivalent product, relevant collection or informative replacement page. Keep a deliberate 404 when no useful equivalent exists. After launch, monitor not-found URLs and external backlink targets.

What breaks in themes and content

Copying HTML from another platform can retain inline styles, scripts, broken assets and inaccessible structure. Pages may look correct on desktop but fail in product templates, search, mobile navigation, translated markets or app blocks. Old image URLs can disappear when the source is decommissioned.

Rebuild content into Shopify’s supported sections and rich-text model. Move assets to governed storage, preserve alt text, set semantic heading hierarchy and test responsive behavior. Inventory theme customizations and assign each to a native setting, app block, custom section or retired feature.

What breaks in checkout and payments

Payment methods, authorization timing, fraud settings, tax, shipping, discounts and address validation can behave differently. Test successful and failed payment, partial capture, cancellation, partial refund, full refund, gift card, multiple currencies and accelerated checkout. Confirm payout and fee reconciliation.

Use test mode where supported and controlled live transactions where required. Verify customer emails and staff notifications. Ensure the legal seller, descriptor and policy links are correct before removing the storefront password.

What breaks in shipping and fulfilment

Rates can change because packaged weights, dimensions, origin, zones or carrier credentials are incomplete. Orders may not reach the warehouse, tracking may not return and split fulfilments can notify customers incorrectly. Cut-off and delivery estimates can be mismatched.

Test domestic, remote, international, oversized, free-shipping and no-rate scenarios. Trace an order from checkout to warehouse, label, carrier scan, tracking, delivery, return and inventory restock. Define manual fallback for integration failure.

What breaks in integrations

Apps may recreate familiar functions with different data and triggers. Webhooks can arrive more than once or out of order. API fields, rate limits and identifiers differ. A launch can generate bulk “new customer” or “new order” automations and spend marketing budget incorrectly.

Create an integration register with event, source, destination, authentication, retry, idempotency, error queue, owner and monitoring. Keep external automations disabled during bulk migration unless they are designed to distinguish imported records. Replay test events and prove duplicate handling.

What breaks in analytics and advertising

Page paths, checkout events, attribution and consent state change. Duplicate tags can double sessions or purchases, while missing server-side or post-checkout events can under-report revenue. Product feed identifiers may change and break campaign history.

Write a measurement plan before implementation. Define event names, parameters, consent behavior, source of revenue truth and product identifiers. Compare platform orders, analytics purchases and advertising events daily after launch, allowing for known timing and attribution differences.

What breaks in finance

Shopify sales, payment captures and payouts represent different events. Historical imports, taxes, discounts, gift liabilities, refunds and fees can shift reporting. If the accounting connector activates before mappings are approved, it can post duplicate or incomplete journals.

Reconcile opening inventory, customer liabilities, payment clearing and migrated order totals. Start the accounting integration in a controlled period. Document cut-off dates and prevent source and Shopify from posting the same sale.

Migration test strategy

Use four test layers: field-level data validation, functional storefront testing, integration event testing and end-to-end business journeys. Automate counts and checksums where possible. Manual sampling should target high-value and complex records.

Maintain a defect log with severity, object, source record, cause, fix, rerun status and owner. Repeat the entire migration on a fresh destination or reset dataset; a one-time hand-corrected store does not prove the process.

Cutover plan

Seven days before

Freeze theme and schema changes, confirm DNS access, lower TTL where appropriate, complete redirect and data rehearsals, finalize support scripts and obtain launch sign-off.

Twenty-four hours before

Run final source exports, disable affected automation, capture inventory and liability balances, validate backups and confirm the rollback decision maker.

Launch window

Apply the final delta, verify counts, enable payments and integrations in sequence, update domains, test critical journeys and monitor errors, orders and warehouse receipt.

First seventy-two hours

Review 404s, checkout conversion, payment failures, inventory exceptions, fulfilment, analytics and customer contacts. Hold a frequent incident review and record every configuration change.

Rollback and recovery

Define rollback triggers before launch: checkout failure, inventory divergence, missing fulfilment, data corruption or unacceptable error rate. DNS rollback alone may not reverse orders already placed. Specify how orders, inventory and customer updates during the window will be reconciled.

Prefer forward fixes for isolated defects and rollback for systemic loss of commerce capability. Keep source access, exports, redirects, credentials and support staffing until the stability period ends.

Acceptance criteria

Require reconciled counts and totals; zero critical data defects; tested customer recovery; validated redirects for priority URLs; working checkout, tax, shipping, payment, fulfilment, refund and notifications; analytics within explained tolerance; finance and inventory reconciliation; monitoring; support runbooks; and approved rollback.

Project Supply perspective

Project Supply treats Shopify migration as ecommerce and digital engineering across data, SEO, integrations, operations and measurement. We design repeatable transformations and evidence-based launch gates rather than relying on manual cleanup after cutover.

Review Project Supply Ecommerce Development at https://projectsupply.in/services/ecommerce-development and Digital Engineering at https://projectsupply.in/services/digital-engineering. For a migration assessment, use https://projectsupply.in/contact and include source platform, catalogue size, customer and order volume, subscriptions, markets, integrations and target launch date.