I contacted Cadimage when the problem happened, they have responded :
" When you choose the Wall Builder accessory object, the error message
pops up because you don't have a fill of that index loaded. This is an
unfortunate ongoing issue with ArchiCAD, but there is a fairly simple
work-around. In the settings dialog, navigate to Appearance > Floor Plan
and use the field to select an available fill "
I still have a few problems, but it works now