Cannot change the type of a mullion created prior to release 4.0 to a corner mullion type. Try deleting the existing mullion and placing a new one.

Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0)

Syntax

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

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

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

See Also