Why Does an Ecommerce Store Lose a Customer’s Cart After Sign-In?

A cart may disappear or change after sign-in if guest and account carts are merged differently, a session cookie is not preserved, or the account belongs to another storefront or currency. This can interrupt a purchase even when inventory is available.

What to check

Reproduce with a new guest session and compare cart contents before and after login. Check cookie scope, session expiration, cart merge rules, storefront, customer group, product availability, and any recent authentication changes.

Recommended next step

Define expected guest-to-account cart behavior and test it across devices and sign-in methods. Preserve valid cart items where policy allows and explain items that cannot be retained because availability or pricing changed.

How Informatix Systems can help

Informatix Systems provides ecommerce software and web development services. We can assess the affected setup, trace the likely cause, and help plan an implementation path. Contact us with the system involved, when the issue began, and non-sensitive error details.