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Customize errors which are not captured by customErrors in ASP.NET 2.0

Customize errors which are not captured by customErrors in ASP.NET 2.0

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Yesterday, I came up with an interesting issue where a customer wanted to customize a 500 error message ("Internal Server Error"). Interestingly, customErrors DID NOT seem to work for StatusCode 500! We just wanted to verify if it works for 404, and it did...

<customErrors defaultRedirect="~/ErrorPage.aspx" mode="On">
            <error statusCode="500" redirect="~/ErrorPage.aspx" />
            <error statusCode="404" redirect="~/ErrorPage.aspx" />
</customErrors>

Ideally, this should have worked... but may be it didn't because some errors are not customizable... http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/80cb8d8d-8fd8-4af5-bb3b-4d11fff3ab9c.mspx?mfr=true

Let us reproduce the error in just a few steps and then we will fix it by creating an HttpModule to handle our scenario.

1. Create a new ASP.NET web service using VB.NET (or C#)
2. Set Service.asmx as start page.
3. Browse to http://localhost/CustomError/Service.asmx?WSDL => This should work
4. Now, browse to http://localhost/CustomError/Service.asmx?WSDL=12 => This should fail with an error code 500 and description "Internal Server Error"

So, now since we are able to repro this error pretty easily, we will start the next step of fixing this and ensure that whenever this happens, we are redirected appropriately to the ErrorPage.aspx.

1. Start by creating a custom page called ErrorPage.aspx under your project folder directly.
2. Under the App_Code folder create a VB class file called ErrorModule.vb and paste the following code...

Imports Microsoft.VisualBasic
Public Class ErrorModule
    Implements IHttpModule
    Public Sub Dispose() Implements System.Web.IHttpModule.Dispose
        'Hmmm... let it be!
    End Sub
    Public Sub Init(ByVal context As System.Web.HttpApplication) Implements System.Web.IHttpModule.Init
        AddHandler context.EndRequest, AddressOf ErrorRedirector
    End Sub
    Public Sub ErrorRedirector(ByVal sender As Object, ByVal e As EventArgs)
        Dim myApp As HttpApplication
        Dim myContext As HttpContext
        Try
            myApp = CType(sender, HttpApplication)
            myContext = myApp.Context
            If myContext.Response.StatusCode.ToString = 500 Then
                myContext.Response.Redirect("ErrorPage.aspx")
            End If
        Catch ex As Exception
            'I don't wanna catch it
        Finally
            myApp = Nothing
            myContext = Nothing
        End Try
    End Sub
End Class

3. In your web.config file paste the following code...

  <httpModules>
   <add name="MyErrorModule" type="ErrorModule"/>
  </httpModules>

4. Compile your project

Now, if you open your browser and browse to http://localhost/CustomError/Service.asmx?WSDL=12, even though you get a 500 error from IIS, you should be redirected to http://localhost/CustomError/ErrorPage.aspx

Yes, it is that simple :o)

Cheers,
Rahul

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  • By the way, I forgot to add this link...

    Displaying Gentle Error Messages with ASP.NET ->  

    http://msdn.microsoft.com/coding4fun/web/misc/article.aspx?articleid=1378666&title=Displaying+Gentle+Error+Messages+with+ASP.NET

  • if you thought that all server error can be handled by custom errors in ASP.Net, think again!! ...

  • I have been pretty busy lately and the last week has flown by on me. I have been spending some of my

  • Odd that CustomErrors can't catch a 500 code.

    Well, glad you posted it.

  • Yes Mads, I agree!

    Honestly speaking even I don't know the root cause it. If I come to know about it anyhow, I will definitely post it!

    Thanks for your comments though :)

    Cheers,

    Rahul

  • You can do this in the Application_Error method in Global.asax file and needn't use a separate HttpModule for it.

    Shiva

  • Hi Shivap...

    Can you please share the code related to Application_Error?

    Thanks,

    Rahul

  • Had an unusual one today. (For me, anyway.) I have a little app at work that for various reasons has to impersonate an identity. For the time being, I do this with this element in the Web.config file:

  • I have been pretty busy lately and the last week has flown by on me. I have been spending some of my

  • The above HttpModule doesnot catch unhandled SQLException(if SQLServer is stopped).Please try this and if you have some solution than please post it here.

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