This article describes a known Adobe Commerce 2.4.0 issue with Klarna payment method, where enabling Klarna on-site messaging without specifying a design theme, results in not displaying product pages on the storefront correctly (product pages appear blank).
Prerequisites: Klarna payment method is enabled.
Steps to reproduce:
The page loads successfully with default design theme applied for Klarna on-site messaging.
A blank page is displayed.
If enabling the Klarna on-site messaging, always ensure that the Design theme field is not blank.