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Troubleshooting Inherited Event Handlers in Visual Basic

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This topic lists common issues that arise with event handlers in inherited components.

Procedures

Code in Event Handler Executes Twice for Every Call

  • An inherited event handler must not include a Handles Clause (Visual Basic) clause. The method in the base class is already associated with the event and will fire accordingly. Remove the Handles clause from the inherited method.

    ' INCORRECT 
Protected Overrides Sub Button1_Click( 
    ByVal sender As System.Object, 
    ByVal e As System.EventArgs) Handles Button1.Click

    ' The Handles clause will cause all code 
    ' in this block to be executed twice. 
End Sub

  • If the inherited method does not have a Handles keyword, verify that your code does not contain an extra AddHandler Statement or any additional methods that handle the same event.

See Also

Other Resources

Events (Visual Basic)