ELMAH is a useful NuGet package that provides an HTTP module to automatically log unhandled ("Yellow Screen Of Death") exceptions in your website, and provides a webpage to allow the exceptions to be reviewed. However, your MVC project is likely to use the built-in HandleErrorAttribute filter which, when custom errors are enabled, catches exceptions and renders the default error view. Since the errors are caught, they do not reach the ELMAH HTTP module and are never logged. Get round this by replacing the built-in HandleErrorAttribute with this ELMAHHandleErrorAttribute.