UPDATE - UPDATE
Aquarelle in Auxerre believe this AVIS is actually referring to the non-navigable section of the river north of Cezy where there is a halte, parallel with the canalised section of the Yonne - however, the VNF NAVI app is showing the whole section of the canalised Yonne closed at PK 35 and beyond in both directions, so maybe contact with the VNF if planning that route is advisable 😏
Judy Evans
MV Mon Amie