ith the Carolingians the funerary basilica of Germanus becomes the church of a monastic community under royal protection.
Charles the Bald, king of West Francia (843-877), demonstrates particularly his attachment to the abbey. He accords it diplomas to guarantee its landed property and acted to preserve its privileges.
The king also stayed frequently at the monastery and demonstrated a great veneration for the relics of the bishop-saint.
He is twice present (841 and 859) at the translation of the precious remains at the moment of the construction of a new crypt undertaken by his uncle, Conrad, who wished to thank Germanus for having contributed to his recovery.
The reign of Charles the Bald is for the abbey an architectural and intellectual high point
, which is attested to by the crypt of Conrad, the manuscript production of the monastic school of Auxerre or moreover by the narrative of the Gesta of the city's bishops undertaken by the cathedral canons at this time.