Question:
I've put the following code in global.asax
<%@ Application Language="VB" %> <script runat="server"> Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs) ' Code, der beim Starten der Anwendung ausgeführt wird. End Sub Sub Application_End(ByVal sender As Object, ByVal e As EventArgs) ' Code, der beim Beenden der Anwendung ausgeführt wird. End Sub ' HelpLink Gets or sets a link to the help file associated with this exception. ' InnerException Gets the Exception instance that caused the current exception. ' Message Gets a message that describes the current exception. ' Source Gets or sets the name of the application or the object that causes the error. ' StackTrace Gets a string representation of the frames on the call stack at the time the current exception was thrown. ' TargetSite Gets the method that throws the current exception. ' http://www.developer.com/net/asp/article.php/961301/Global-Exception-Handling-with-ASPNET.htm Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs) ' Code, der bei einem nicht behandelten Fehler ausgeführt wird. 'get reference to the source of the exception chain Dim ex As Exception = Server.GetLastError().GetBaseException() 'log the details of the exception and page state to the 'Windows 2000 Event Log 'System.Diagnostics.EventLog.WriteEntry("source", "MESSAGE: " + ex.Message + "\nSOURCE: " + ex.Source + "\nFORM: " + _ 'HttpContext.Current.Request.Form.ToString() + "\nQUERYSTRING: " + HttpContext.Current.Request.QueryString.ToString() + _ '"\nTARGETSITE: " + ex.TargetSite.ToString + "\nSTACKTRACE: " + ex.StackTrace, System.Diagnostics.EventLogEntryType.Error) Response.Redirect("GeneralError.aspx", False) 'Response.Redirect("GeneralError.aspx") 'Insert optional email notification here... ''this is what we are sending 'Dim post_data As String = "MESSAGE: " + ex.Message + "\nSOURCE: " + ex.Source + "\nFORM: " + _ 'HttpContext.Current.Request.Form.ToString() + "\nQUERYSTRING: " + HttpContext.Current.Request.QueryString.ToString() + _ '"\nTARGETSITE: " + ex.TargetSite.ToString + "\nSTACKTRACE: " + ex.StackTrace 'post_data = HttpContext.Current.Server.UrlEncode(post_data) '' this is where we will send it 'Dim uri As String = "http://localhost/cor_raumplaner/GlobalError.aspx" '' create a request 'Dim request As System.Net.HttpWebRequest = DirectCast(System.Net.WebRequest.Create(uri), System.Net.HttpWebRequest) 'request.KeepAlive = False 'request.ProtocolVersion = System.Net.HttpVersion.Version10 'request.Method = "POST" '' turn our request string into a byte stream 'Dim postBytes As Byte() = Encoding.ASCII.GetBytes(post_data) '' this is important - make sure you specify type this way 'request.ContentType = "application/x-www-form-urlencoded" 'request.ContentLength = postBytes.Length 'Dim requestStream As System.IO.Stream = request.GetRequestStream() '' now send it 'requestStream.Write(postBytes, 0, postBytes.Length) 'requestStream.Close() '' grab te response and print it out to the console along with the status code 'Dim response1 As System.Net.HttpWebResponse = DirectCast(request.GetResponse(), System.Net.HttpWebResponse) 'Response.Write(New System.IO.StreamReader(response1.GetResponseStream()).ReadToEnd()) 'Response.Write(response1.StatusCode) End Sub Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs) ' Code, der beim Starten einer neuen Sitzung ausgeführt wird. End Sub Sub Session_End(ByVal sender As Object, ByVal e As EventArgs) ' Code, der am Ende einer Sitzung ausgeführt wird. ' Hinweis: Das Session_End-Ereignis wird nur ausgelöst, wenn der sessionstate-Modus ' in der Datei "Web.config" auf InProc festgelegt wird. Wenn der Sitzungsmodus auf StateServer ' oder SQLServer festgelegt wird, wird das Ereignis nicht ausgelöst. End Sub </script> Then i've added a new page, and made it generate an error, like this:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Dim mylanguage As String = Session("Language") Dim iLength As Integer = mylanguage.Length End Sub Now, the problem is seems to be that the application error handler in global.asax doesn't get called, instead I receive a standard exception: "Object reference not set to an instance of an object"
Why ? Shouldn't it call the error handler and redirect to the GeneralError.aspx page ?
Solution:1
In your web.config file make sure you have Debug=false If it's turned on you'll see all the error messages and your error handler may not work as intended.
Solution:2
When using the AspNetDevelopmentServer shipped with Visual Studio it´ll ignore if the error isn't cleared before continuing outside the Application_Error but in IIS the error is still in the session when exiting the method and thus it´s deemed unhandled by IIS which´ll then display it in its own error page.
To correct this use Server.ClearError() after Server.GetLastError() to make sure you signal the server that You will handle the error.
/ Regards
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