An existing project that previously built without settings.ruiPath stopped working after updating Rhino 9 WIP. I reduced the current failure to a minimal .rhproj containing one Python command.
Using RhinoCode 9.0.26216.12303, omitting ruiPath causes:
20% - Preparing plugin assembly
Build Error: Could not find a part of the path '<folder containing the .rhproj>\'.
The folder and RUI file both exist. Adding the missing reference fixes the build:
"ruiPath": "../Toolbar/Test.rui"
My project is working again, but I wanted to report this because the update appears to have introduced either a regression or an undocumented requirement.
Is ruiPath now intentionally mandatory? If so, could the error identify the missing setting explicitly?