Page_Error does not show Unhandled Exception in WebMethod call by Javascript

Question

Im new to C# ASP.net. I use Monodevelop in Ubuntu to create a simple WebForm.

Default.aspx.cs:

public partial class Default : System.Web.UI.Page
{
    protected void Page_Error(object sender, EventArgs e)
    {
            Exception Ex = Server.GetLastError();
            Console.WriteLine(Ex.Message);
    }


    [System.Web.Services.WebMethod]
    public static string TestUnhandledException()
    {
        throw new Exception("abc");
    }
}

Default.aspx

<%@ Page Language="C#" Inherits="MyFirstWebForm.Default" %>
<!DOCTYPE html>
<html>

<head runat="server">
    <title>Default</title>
    <script>
        function Test() {
            PageMethods.TestUnhandledException(OnSuccessCallback, OnFailureCallback);
        }

        function OnSuccessCallback(res) {}
        function OnFailureCallback() {}
    </script>

</head>

<body>
    <form id='form1' runat='server'>
        <asp:scriptmanager enablepagemethods="true" id="scpt" runat="server"> </asp:scriptmanager>
        <asp:button id="Button1" runat="server" text="Initialize" OnClientClick='Test();return false;'/>
    </form>

</body>
</html>

The method TestUnhandledException() works fine, but as I debug, there is no exception message show and Page_Error() never runs.

Do I miss something ? How should I log the unhandled exception in ASP.NET webform ? I appreciate any help.

Update: The exception throw by Page_Load is caught by Page_Error but the one thrown by [WebMethod] does not.

Tran Ngu Dang · Accepted Answer · 2016-11-11 12:45:10Z

1

It seems it is not simple to catch unhandled exception thrown by WebMethod. From this post:

you can't just add a few lines of code to the Global.aspx.cs file in the Application_Error event handler method to log unhandled exceptions because the ASP.NET Web Services pipeline bypasses this event so it can return all the exceptions back to the caller.

So probably the most simple way is to surround the method with try-catch block as shown in the post

answered Nov 11, 2016 at 12:45

Tran Ngu Dang

2,6606 gold badges31 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Damith Asanka · Accepted Answer · 2016-11-11 09:44:54Z

0

Did you check inner Exception ?. your exception message should be in there

answered Nov 11, 2016 at 9:44

Damith Asanka

96410 silver badges12 bronze badges

1 Comment

Tran Ngu Dang Over a year ago

The problem is as I debug, Page_Error() never runs in the first place

Collectives™ on Stack Overflow

Page_Error does not show Unhandled Exception in WebMethod call by Javascript

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related