ActiveViewIndex se está estableciendo como 'X'. Debe ser menor que el número actual de controles View 'Y'. Para vistas agregadas dinámicamente, asegúrese de que se agregan antes del evento Page_PreInit o en el mismo.
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English version
ActiveViewIndex is being set to 'X'. It must be smaller than the current number of View controls 'Y'. For dynamically added views, make sure they are added before or in Page_PreInit event.
.Net Framework