"Family '[Name]' cannot be upgraded and must be deleted. To fix the file in the older version of Revit, try loading newer versions of these families: [Names]."
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.1.0.0 (26.1.0.34)
Syntax
C#
public static FailureDefinitionId FamilyCannotBeUpgraded { get; }