Avatar of flynny
Flag for United Kingdom of Great Britain and Northern Ireland asked on

Updating AJAX dll on site

Hi all,

Sorry for being dumb here.

I'm getting the following error after updating the AjaxControlToolkit.dll on a site, after copying the new DLL to the bin folder;

Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.

After googling around to fix the issue, I changed the application pool on IIS (Version 7.5.7600) fromt he default site named pool to be ASP.NET Classic (I have also tried Integrated).

However I then get a 500 error when I try to navigate the site?

Can anyone direct me in the right direction please?
Microsoft IIS Web ServerASP.NET

Avatar of undefined
Last Comment

8/22/2022 - Mon


Make sure you install the correct version of the AjaxControlToolkit:

Version 3.0.20229 2008-02-29 release of the AJAX Control Toolkit targets the official release of .NET Framework 3.5 and Visual Studio 2008.

Version 1.0.20229 You can also download the Toolkit for .NET Framework 2.0, ASP.NET AJAX 1.0 and Visual Studio 2005.

Version 3.0.40412

April 12, 2010 release of the AJAX Control Toolkit for ASP.NET 3.5 Service Pack 1 and Visual Studio 2008 SP1.

Version 4.1.51116.0

Nov 16 2011 release of the AJAX Control Toolkit for ASP.NET 4.0 and Visual Studio 2010

Version 4.1.60919

September 2012 release of the AJAX Control Toolkit for ASP.NET 4.5 and Visual Studio 2012

Hi gaurav05,

Thanks for the reply.

sorry, do you mean is installed on the server?

I have browsed to programs and featutes (the server is running windows web server 2008).

Currently installed is Microsoft .NET Framework 4 extended and Microsoft Framework 4 Client Profile.

There is also Microsoft ASP.NET 2.0 AJAX Extensions 1.0 installed (there is no installed in the Binary .NET 4 zip i downloaded?) Do I need to physically run an installer on the server?

The original DLL file which was working was 3.5.40412.2

however I wanted to use the MultiHandleSlider which did not appear to be in this release? So I have downloaded the version, which is causing the issues.

I assumed by having .NET 4 installed this would support itdo I need to install anything further?

Log in or sign up to see answer
Become an EE member today7-DAY FREE TRIAL
Members can start a 7-Day Free trial then enjoy unlimited access to the platform
Sign up - Free for 7 days
Learn why we charge membership fees
We get it - no one likes a content blocker. Take one extra minute and find out why we block content.
Not exactly the question you had in mind?
Sign up for an EE membership and get your own personalized solution. With an EE membership, you can ask unlimited troubleshooting, research, or opinion questions.
ask a question


I uploaded the 3.5 version and all is back to normal.

Is there any benefit from me updating to 4.0?

Also I seem to have 4.0 installed and like i mentioned earlier i set the pool to be 4.0 but this didnt seem to work? any reason why you think this owul dhappen?
All of life is about relationships, and EE has made a viirtual community a real community. It lifts everyone's boat
William Peck