Indirect reference is being made to assembly System.Web.Extensions version

The full error message is:

Error 1 Indirect reference is being made to assembly System.Web.Extensions version, which contains ‘AjaxControlToolkit.CalendarExtender’. This Project references a prior version of System.Web.Extensions version 1.0.61025.0. To use ‘AjaxControlToolkit.CalendarExtender’, you must replace the reference to System.Web.Extensions with version or higher.

After some time finding for the cause, I realize that this is due to the me using the newer version of AjaxControlToolkit.dll. I should use the older version AjaxControlToolkit.dll for my ASP.NET 2.0 development.


Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation

The full error message is

“Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application.”

This is probably due to you using MsgBox(“so message here.”) for your web application. I learn that you can only use MsgBox for window form application.

So, the solution is to think of other way to display a message to the user.

ASP.NET 2.0 Software Engineering VB.NET

Hide your source code at the browser when hit error

I got a little anxious and embarrassed to see my source code exposed at the browser when I got an error.

Managed to find out that this is due to some setting at the web.config. I just need to set debug to false.

[sourcecode language=”html”]
<compilation debug=”false” />


Unable to send to all recipients … Mailbox unavailable. The server response was: 5.7.1 Unable to relay for …

Managed to fix it by going to IIS > Default SMTP Virtual Server > Property > Access > Relay


Even though I still not able to receive the mail I sent out yet, but there is no more error message when I use VB.NET code (System.Net.Mail.MailMessage) to send it.

When I went to C:InetpubmailrootQueue, I saw that the mail was there. My next goal is to make sure I receive this email. I think the next I need to look into SMTP thingy at my code.


Error: Failure sending mail … Unable to connect to the remote server

During my development, I bound into this error. The short error message is “Failure sending mail”. The long one is

Failure sending mail. —> System.Net.WebException: Unable to connect to the remote server —> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)

I googled a bit and found out that this is could be due to my SMTP services was not started. So, I went to start it but I got another message “Could not start the Simple Mail Transfer Protocol (SMTP) service on Local Computer. Error 1068: The dependency Service or group failed to start”.

So, I googled again and found out that this could be due to my IIS services was not started and so I went to start it. And guess what, there was still another error. I didn’t manage to save the error message this time.

Without giving up, I googled again and got tips to check on Event Log to see if there is any thing I can get from there. When I opened it, I saw nothing. Then, I went back to Window Services and found out that Event Log was disabled! I enabled it back, that is it. After that, I can start IIS services and SMTP services liao.

Wait a minute … as I continued with my development, I got another message, “Unable to send to all recipients”. This is will be shared in the next post.