Attributes cannot be generics or types nested inside generics
An attribute is declared as a generic type, or within a generic type.
Visual Basic and the .NET Framework do not currently support any combination of attributes and generic types. This means the following limitations apply:
An attribute cannot be a generic type or be declared within a generic type.
An attribute cannot inherit from a generic class, nor can a generic class inherit from an attribute.
When you apply an attribute, you cannot supply an argument that is any of the following:
A generic type,
A type constructed from a generic type,
A type parameter of a containing type, or
A type constructed from a type parameter of a containing type.
Error ID: BC32067
To correct this error
If the attribute declaration includes the Of keyword and a type parameter list, then remove them.
If the attribute declaration appears inside a generic type, then move it to where it is not inside any generic type.
See Also
Concepts
Attributes Overview in Visual Basic