Volkswagen has modified its We Connect login flow to require client assertion, blocking authentication in the homeassistant-volkswagencarnet integration per GitHub issue 967. Users confirm successful logins via the official Volkswagen app and https://vwid.vwgroup.io/ yet receive the error "Anmeldung bei Volkswagen Connect nicht möglich" when using third-party credentials. The report specifies no MFA, valid subscriptions, and verified portal access.

The GitHub issue documents the failure after prior working releases of the integration, with traceback logs showing expired authentication that cannot be renewed through the same endpoint. This aligns with documented OAuth changes in Volkswagen's ID.3 and ID.4 API references from 2023 developer notes. Comparable disruptions appeared in other reverse-engineered endpoints for Seat and Skoda Connect services.

Primary logs in the issue contain no evidence of terms acceptance or subscription problems as root causes. Volkswagen's shift matches patterns in its 2022-2024 service updates that introduced assertion-based flows for enhanced token validation.