Cheikh T Sylla:
There is a problem with the 3D Script in the library part
m_Rail Balustrade.gsm, which could be an Object, or could be a macro called by an object (from the name it seems like it would be part of a stair). You will need to narrow down which Object is causing the error (by using the Marquee Tool or Layers) to find the problematic Object, then alter its parameters to fix the issue.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David