Extension methods can be defined only in modules

This error occurs when an extension method has been defined outside a module. In Visual Basic, all extension methods must be defined within standard modules.

Error ID: BC36551

To correct this error

  • Place the extension method in a module.


The following example extends the String class, adding a Print method.

Imports StringUtility  
Imports System.Runtime.CompilerServices  
Namespace StringUtility  
    <Extension()> _  
    Module StringExtensions  
        <Extension()> _  
        Public Sub Print (ByVal str As String)  
        End Sub  
    End Module  
End Namespace  

See also