Family's Category can't be changed because the Family contains Shared Parameters which are not permitted in the new Category.

Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 24.0.0.0 (24.0.0.0)

Syntax

C#
`public static FailureDefinitionId FamilyNoExternalParametersWarning { get; }`

Visual Basic
`Public Shared ReadOnly Property FamilyNoExternalParametersWarning As FailureDefinitionId Get`

Visual C++
`public: static property FailureDefinitionId^ FamilyNoExternalParametersWarning { FailureDefinitionId^ get (); }`

See Also