There are undefined Spaces in the model! Recommend creating a Space schedule and checking the Area parameter of each Space for warnings.
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.4.0.0 (26.4.0.0)
Syntax
C#
public static FailureDefinitionId UndefinedSpaces { get; }