Misconfigured carriers and shipping costs on PrestaShop
A carrier that disappears at checkout, a shipping cost that doesn't match the cart weight, a delivery zone with a gap: PrestaShop's carrier configuration is more detailed than it looks, and a single misconfigured rule is enough to block a sale.
How PrestaShop calculates shipping costs
Each carrier created in ps_carrier is tied to price brackets defined by weight or price, themselves attached to a geographic zone. If a customer's delivery address falls in a zone not covered by the carrier, or if the cart weight exceeds the last defined bracket, PrestaShop silently removes that carrier from the checkout options, with no explicit error for the customer.
External carrier modules (Mondial Relay, Colissimo, Chronopost, among others) add another layer: they sometimes calculate their own rate via an API call to the carrier, and an authentication error or a temporarily unavailable service on the carrier's side can make the option disappear without anything looking broken on PrestaShop's side.
The actionCarrierUpdate hook fires when a carrier is edited, and some modules use it to automatically recalculate rate grids: disabling or updating a module can therefore change a displayed rate without any manual action on your part.
Cases I handle
- No carrier offered for certain delivery addresses
- Shipping cost at zero or inconsistent for a heavy cart
- Pickup point not found, or the selection map won't load
- A carrier disappearing only for certain countries or postcodes
- Fixed delivery rates that no longer track the real carrier's grids
How I check
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Reproducing the exact case
I simulate an order with the exact weight, country and postcode reported by the blocked customer, to reproduce the behaviour rather than guess.
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Checking zones and brackets
I check that the relevant geographic zone is actually covered and that the weight or price brackets go up to the amount actually needed.
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Checking carrier modules
I test external carrier modules' API calls to rule out an authentication issue or an unavailable service.
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Adjusting the rules
I fix the relevant brackets, zones or restrictions and re-test with the same scenario to confirm the carrier is available again.
What I can also set up
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Custom rate grids
Shipping cost rules combining weight, cart value and zone, aligned with your actual carrier contracts.
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Pickup point delivery
Integrating or fixing pickup point selection modules, with checks on the map and point availability.
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Free shipping rules
Setting free-delivery thresholds consistent with your margin, without breaking the other carriers on offer.
Describe your need in one minute
A few targeted questions so I can reply with an estimate rather than another questionnaire.