Judgment of the Court (Seventh Chamber) of 23 January 2025.#Criminal proceedings against EX.#Request for a preliminary ruling from the cour d'appel de Liège.#Reference for a preliminary ruling – Migrant workers – Social security – Applicable legislation – Posted workers – Documents in the form of A1 certificates allegedly issued by the institution competent to issue those certificates – Regulation (EC) No 883/2004 – Article 76(6) – Obligation of the authorities of the host Member State to initiate a dialogue and conciliation procedure for the purpose of determining whether fraud has occurred.#Case C-421/23.