Switching 3PLs without losing orders: a practical cutover checklist

The risky part of changing fulfillment providers is the overlap. Inventory is leaving one warehouse, the new warehouse is learning your products, and customers are still checking out.

A pallet can arrive safely while the orders attached to it end up in the wrong queue. A stock adjustment can make units available online before anyone can pick them. Two connected warehouses can both believe they own the same order.

Treat your move as two coordinated projects: transferring physical inventory and transferring responsibility for orders. Give each project an owner, a written sequence and a clear point at which the new 3PL takes over.

Choose how you will bridge the move

Start with your best sellers and the number of days they can keep shipping during the transition. Your options usually include:

• Send fresh supplier inventory to the new warehouse while the old warehouse works through its remaining stock.
• Transfer inventory in waves, keeping enough stock behind to support orders during transit and receiving.
• Pause fulfillment briefly and move everything together, with a clear customer-facing dispatch expectation.

Choose the method SKU by SKU if necessary. Slow-moving products may transfer in one load while your highest-volume products need overlapping stock.

Calculate coverage using expected daily unit demand, not average daily orders. An order containing three units consumes three units. Account for demand spikes, existing commitments and the receiving time agreed with the destination warehouse. Carrier delivery confirmation alone should never be your signal to promise immediate dispatch.

Build one product file before moving stock

Ask the new 3PL to confirm its required import format. Prepare a clean record for every sellable variant, including the exact SKU, product name, barcode, unit of measure, unit dimensions and weight, and special handling instructions.

Then resolve the awkward products deliberately:

• Bundles: Does the warehouse pick components, or receive a finished kit?
• Multipacks: Does the barcode identify one unit or one case?
• Similar variants: Can a receiver distinguish the sizes, scents or colours without opening every package?
• Controlled stock: Which products need lot, expiry or serial-number tracking?
• Packaging: Which orders need specific cartons, inserts or gift presentation?

Use photographs where words leave room for interpretation. Send a sample label to the new warehouse and have it scanned before asking your supplier to label thousands of units.

Give every open order an owner

Take an order snapshot at the agreed cutover time, including the timezone. The list should show the order number, items, quantities, payment or hold status, assigned warehouse and next action.

Sort open orders into practical groups: already shipped, being picked, waiting on stock, held for review, cancelled, and ready to transfer. Handle partially fulfilled orders at the line-item level. A simple whole-order label can hide an item that still needs shipping.

Agree how the old warehouse confirms that a transferable order has been released from its queue. Do this before the new warehouse receives a fulfillment instruction. Keep the original order reference so both teams can trace what happened.

Also decide who handles late tracking updates, cancellations and customer address changes. Changing warehouses should not leave customer service guessing which team can still stop a parcel.

Test the storefront and warehouse connection

Shopify tracks inventory separately by location, and a product must be active at a location to be sellable or fulfillable there. Its multi-location inventory guidance explains the distinction between recording stock and activating a product.

Have the person responsible for your integration verify the receiving warehouse, product assignments, inventory updates, shipping profiles and order-routing configuration. Shopify's order-routing documentation explains how rules determine the fulfillment location.

Run a small, controlled test set agreed with the 3PL:

Use a test method appropriate to the integration, and keep test orders away from real customers. Check the result in both systems; seeing the order in one dashboard is only half the test.

Reconcile the inventory that actually moved

Record what the old warehouse counted and dispatched by SKU, carton or pallet. Keep damaged stock and stock reserved for remaining orders separate from the transfer quantity.

At the destination, compare dispatched quantities with accepted receipts, rejected units and unresolved discrepancies. For example, if a transfer lists 500 units and the new warehouse records 488 accepted plus 8 damaged units, four units remain unexplained. Do not make all 500 available for sale to force the totals to agree.

Assign someone to investigate discrepancies using dispatch records, carton counts and photographs. Agree how much undisputed inventory can be released while a discrepancy remains open.

Use a release checklist, then monitor the first orders

Before turning on the new order flow, require named owners to confirm that:

• Priority products have been received, counted and made available for picking.
• Inventory quantities and storefront availability have been checked.
• The test orders passed and outstanding issues have owners.
• Each open order belongs to one fulfillment team.
• Customer service has the new escalation contacts and dispatch expectations.
• Someone can pause new routing if a material problem appears.

For the first operating days, compare orders expected at the new warehouse with orders imported, held and shipped. Investigate missing order numbers directly. A shipment count alone can look healthy while individual orders are stranded.

Keep the old provider's closeout work visible until remaining stock, returns, invoices and tracking exceptions are resolved. If rollback becomes necessary, pause new routing and reconcile order ownership before switching it again; a simple toggle can recreate duplicate shipments.

Bring this checklist to your onboarding call with 247 Fulfillment, together with your SKU file, open-order report and proposed move date. Those three inputs give the team something concrete to plan around.