I am using the ajax control toolkit update panel for a site. I have noted that when users use my site with the Mozilla browser and click on one of the buttons in the update panel that a double postback occurs. I have been unable to trace the source of this problem and I have been unable to replicate it in IE 6.0. Has anyone come across this problem before?

Mike55.

Are you able to reproduce the problem in FireFox yourself?  ASP.NET AJAX definitely works fine cross browser. 

I managed to locate the actual source of my problem; it was the following piece of vb.net/javascript code that caused the problem:

'Prevent the user from double clicking on the save button.
    Private Sub PreventDoubleClick()
        Dim sb As System.Text.StringBuilder = New System.Text.StringBuilder()
        sb.Append("if (typeof(Page_ClientValidate) == 'function') { ")
        sb.Append("if (Page_ClientValidate() == false) { return false; }} ")
        sb.Append("this.value = 'Please wait...';")
        sb.Append("this.disabled = true;")
        sb.Append(Page.GetPostBackEventReference(btnSave))
        sb.Append(";")
        btnSave.Attributes.Add("onclick", sb.ToString())
    End Sub

 Once this was removed all worked as per expected.  I had to find another way of working around the problem using the ajax UpdateProgress control.

 Mike55.

The example here includes disabling a button trigger for the duration of a partial postback and then re-enabling it at the end.  Might be of use to you, in replacing that code. 

I have had a similar problem with the UpdatePanel and double postbacks.  However these double postbacks occured in all browsers.  I was able to finally figure out the problem and it was caused by double wireing up of the controls to the code behind event. 

For example:

At the top of the page i had:

AutoEventWireup="false"

then my button:

<asp:Button ID="btnSave" runat="server" Text="Save" OnClick="btnSave_Click" />

then the actual code behind

The problem was that the button had an OnClick specified, and in the code behind it also had the Handles btnSave.click.   By removing the Handles btnSave.click I was able to remove the extra postback.  You could also change the AutoEventWireup to True and then just remove the OnClick reference on the button.

I hope this help

echo7

Yes. This is bug only happend in firefox, when you enable or disable buttons in UpdatePanel.

The golden rules is alaways disable button, or have some method handel the duplicate submit.