The selected wall type/shape isn't supported for attaching a wall to a stair. To continue, detach the wall from the stairs' components.
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.2.0.0 (26.2.0.0)
Syntax
C#
public static FailureDefinitionId WallTypeUnsupportedError { get; }