Hi dufour
It's hard to say where is the problem.
Nevertheless, I'll try to give you my point of view
As the first error message is located on the first time step
CNTPRE (ARTEMIS) : PRECONDITIONNEMENT DIAGONAL NON APPLIQUE (UN ELEMENT DIAGONA
L DE LA MATRICE EST NEGATIF OU NUL)
I suppose the problem comes from the initial water level.
Are you sure there is no tidal flats on your model (eventually due to the initial water level)?
Regards