Thanks, this worked.

For me, the problem was that I originally had an application targetting .NET 2.0, and then changed it to .NET 3.5... Bit of a n00b thing to miss I suppose!

I remove the assembly directive in master page and it work good! But I did it in SharePoint 2007

Hi .. Just remove the following red line from your page source & it'll work Just fine .. PEACE

Look if you have an extra assembly

<add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>

if so comment or remove the line.

In my case, this error occurred when, for some reason, my web project suddenly referenced a GAC version of AjaxControlToolkit and the BIN version (the original that I had.)

I didn't know since when the AjaxControlToolkit was registered in the GAC (probably when I installed 2008 express editions side-by-side with my Visual 2005 Pro), but when I removed the reference from the AjaxControlToolkit from the GAC, the problem disappeared.

I only had to check this from the Property Pages of my web project.

Anyways I've decided to start a new project and my new projects don't show ajax projects anymore (Odd). So I started a blank website.

The page I created was an "AJAX web form" and tried to run it an it gave me the following issue.

Unknown server tag 'asp:ScriptManager' (the other application was giving me the ambiguous error)

so i removed the script manager and everything worked fine.

added a new script it created a web config and buala the following lines of codes appeared in the web.config. So I pasted the lines on my other web.config and it worked!!! Then I removed the lines and it worked.... it only took me 6 hours and I have to be up in 3 hours! Fun! Tanx Microsoft where would I be without you! :)

 PS: when I tried doing this in the application those lines never appeared. In fact nothing happened in the web config (another odd one).

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
      </dependentAssembly>
    </assemblyBinding>
  </runtime>

kyleq:

At various times I get an error message telling me that the server tag "asp:ScripManager is " is ambiguous.  It may also happen with other tags including UpdateProgress and UpdatePanel.  How do I fix this?

I am running Visual Web Developer 2008 with Framework Version 3.5.

Here it is July of 2009 and I just got the same error.  It may not be worth using Ajax if you can't control the controls, and it has a programming interface that controls itself.  This is Bizarre.

I found a way to resolve this issue the ambiguous assembly issue that has worked for several projects I have worked on over the last year.  If you have access to both Visual Studio 2005 and 2008 you can use those tools to upgrade a 2.0 web config to 3.5.  What I do is create a new web project in 2005, copy the web.config from my project over the web.config in the new 2005 project, then open the 2005 project in 2008.  You will be prompted to upgrade the 2005 / ASP.Net 2.0 project to 2008 / ASP.Net 3.5.  Convert the project and it should work.

If you need an empty 2005 project, let me know, and I should be able to create one and post it on my website for you to download.  It's a hack but it has work really well for me.

AJAX is definitely worth learning to use.  However, I would strongly recommend you learn how it is supposed to work and not just use UpdatePanel controls everywhere.  I did that for a few projects before I found out the overhead and inefficiency involved.  When you use an update panel, the entire page is re-rendered on the web server for every event - every button click, etc.  Then just the update region is sent to the browser.  The ViewState can be very large for even small pages because the state of all the controls, even ones not affect by the content inside the UpdatePanel needs to be passed from client-to-server AND server-to-client for every event.

For some of my newer projects I have abandoned most of what ASP.Net does for client-side JavaScript code using JQuery and passing data back and forth in JSON format.  I'm basically coding in a different language and doing everything the hard way, but it is very fast and efficient.  For smaller projetcs I still use ASP.Net and UpdatePanels.  It's all a matter of trade-offs and what fits best for a project.

-Pat

Thank you for your help and honest opinion.

I started 10 years ago with vb script (spaghetti code), and most of the time even in .NET Server Side Programming, I will code manually, only because I already know what the code is going to do.   With Visual Web Developer, it seems the interface insists on making decisions for me.  I guess that my "old school" ways cause me to maintain control more often than not.

I'll let you know what happens. Thanks again !

Thank u for helping me ,its working