Is Response.End() considered harmful?
.net, asp.net
Solution
If you had employed an exception logger on your app, it will be watered down with the `ThreadAbortException`s from these benign `Response.End()` calls. I think this is Microsoft's way of saying "Knock it off!".
I would only use `Response.End()` if there was some exceptional condition and no other action was possible. Maybe then, logging this exception might actually indicate a warning.
Problem
This KB Article says that ASP.NET's `Response.End()` aborts a thread. Reflector shows that it looks like this: ``` public void End() { if (this._context.IsInCancellablePeriod) { InternalSecurityPermissions.ControlThread.Assert(); Thread.CurrentThread.Abort(new HttpApplication.CancelModuleException(false)); } else if (!this._flushing) { this.Flush(); this._ended = true; if (this._context.ApplicationInstance != null) { this._context.ApplicationInstance.CompleteRequest(); } } } ``` This seems pretty harsh to me. As the KB article says, any code in the app following `Response.End()` will not be executed, and that violates the principle of least astonishment. It's almost like `Application.Exit()` in a WinForms app. The thread abort exception caused by `Response.End()` is not catchable, so surrounding the code in a `try`...`finally` won't satisfy. It makes me wonder if I should always avoid `Response.End()`. Can anyone suggest, when should I use `Response.End()`, when `Response.Close()` and when `HttpContext.Current.ApplicationInstance.CompleteRequest()`? ref: Rick Strahl's blog entry. Based on the input I've received, my answer is, Yes, `Response.End` is harmful, but it is useful in some limited cases. - use `Response.End()` as an uncatchable throw, to immediately terminate the `HttpResponse` in exceptional conditions. Can be useful during debugging also. Avoid `Response.End()` to complete routine responses. - use `Response.Close()` to immediately close the connection with the client. Per this MSDN blog post, this method is not intended for normal HTTP request processing. It’s highly unlikely that you would have a good reason to call this method. - use `CompleteRequest()` to end a normal request. `CompleteRequest` causes the ASP.NET pipeline to jump ahead to the `EndRequest` event, after the current `HttpApplication` event completes. So if you call `CompleteRequest`, then write something more to the response, the write will be sent to the client. Edit - 13 April 2011 Further clarity is available here: - Useful post on MSDN Blog - Useful analysis by Jon Reid