text: ---
  title: "Conversion operators cannot convert from an interface type"
  ms.date: 07/20/2015
  f1_keywords: 
    - "vbc33029"
    - "bc33029"
  helpviewer_keywords: 
    - "BC33029"
  ms.assetid: 0d0ee461-dd48-424b-b83a-484bfc648d4d
  ---
  # Conversion operators cannot convert from an interface type
  
  A conversion operator is declared with an interface type for the parameter.  
    
   At compile time, Visual Basic considers a predefined conversion to exist from any interface to any reference type. Such a conversion might fail at run time, but the compiler cannot predict run-time results, so it allows any such conversion to compile.  
    
   Because the compiler considers this conversion to be already defined, it does not allow you to redefine it.  
    
   **Error ID:** BC33029  
    
  ## To correct this error  
    
  - Remove this operator definition entirely. It is already predefined.  
    
  ## See also
  
  - [Operator Procedures](../programming-guide/language-features/procedures/operator-procedures.md)
  - [Operator Statement](../language-reference/statements/operator-statement.md)
  - [How to: Define an Operator](../programming-guide/language-features/procedures/how-to-define-an-operator.md)
  - [How to: Define a Conversion Operator](../programming-guide/language-features/procedures/how-to-define-a-conversion-operator.md)
  