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## Atomic storefront session rotation

Following [Single active storefront session per customer](/developer/changelog/2026/9/23), we are rolling out a reliability improvement to how a second storefront sign-in invalidates a customer's earlier session. Rotating the customer session token and its expiry now happens as one all-or-nothing update, so a partial failure during sign-in no longer leaves an earlier session for the same customer working.

* **All-or-nothing rotation** - when a customer signs in again on your storefront, the write that ends their earlier sessions either fully completes or fails, instead of silently leaving the old session active.
* **Clean failure instead of silent success** - if the rotation write cannot complete, the sign-in reports the failure and the failure is logged; the old token is never half-updated.

For details, see [Customer login](/developer/docs/storefront/guides/customer-authentication/customer-login).