How to better debug a WebService asmx -- 500 Internal Server Error

I need the errors from my web service sent directly to the client in Json format so I can read exactly what error is being thrown. How do I do this please?

This is what I keep getting in Fiddler

Runtime Error 
Description: An application error occurred on the server. The current 开发者_JAVA百科custom error settings for this application prevent the details of the application error from being viewed. 

Details: To enable the details of this specific error message to be viewable on the local server machine, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "RemoteOnly". To enable the details to be viewable on remote machines, please set "mode" to "Off".


<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="RemoteOnly"/>
    </system.web>
</configuration>

Server code

  <WebMethod(EnableSession:=True)> _
<ScriptMethod(ResponseFormat:=ResponseFormat.Json)> _
 Protected Function PopulateUsers() As IDictionary(Of String, String)

        Dim users As New Dictionary(Of String, String)

        Try
            Dim arry As ArrayList =  UserController.GetUsers(0, True)
            For Each objUser As Users In arry 
                userrole.Add(CStr(objUser.UserID), objUser)
            Next
        Catch ex As Exception
            Dim ur As New Dictionary(Of String, String)
            Dim s As New User
            s.DisplayName = ex.GetBaseException.StackTrace
            s.UserID = 1
            users.Add(ex.GetBaseException.Message, s)
            Return s
        End Try

        Return users 
    End Function

Make sure you have proper error handling in your web service. In case of any error, convert your error object into a well formed json object and send it. In the client side, success handler will only be invoked but you need to check whether the response contains the error object or the actual response and act accordingly.

There is error in your catch block, try this

Protected Function PopulateUsers() As IDictionary(Of String, String)

        Dim users As New Dictionary(Of String, String)

        Try
            Dim arry As ArrayList =  UserController.GetUsers(0, True)
            For Each objUser As Users In arry 
                userrole.Add(CStr(objUser.UserID), objUser)
            Next
        Catch ex As Exception
            Dim ur As New Dictionary(Of String, String)

            ur.Add("ERROR", ex.GetBaseException.StackTrace)
            Return ur
        End Try

        Return users 
    End Function

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