ASP.NET Ajax client-side framework failed to load

[Jerry Jansen]

I have a web site in ASP.NET 3.5 that runs fine using ver. 2009.1208.35 of Telerik.Web.UI.dll.

I only replace the Telerik.Web.UI.dll and Telerik.Web.Design.dll with the latest ver. 2009.1314.35 and viewing a page in the browser I get the Error: ASP.NET Ajax client-side framework failed to load.

I copy back ver. 2009.1208.35 of the dlls and viewing the same page in the browser works fine!

Using VS 2010 on Win 7 computer. Web.config does not have any version numbers for the Telerik settings.

Both versions are in the GAC.

Why does 1208 work and 1314 not work?

[Martin]

Hello Jerry,

Here is a short quote from our documentation:

Problem:

Using RadControls with RadScriptManager on your login page throws one of the following errors:

• ASP.NET Ajax client-side framework failed to load
• 'Sys' is undefined
• “Telerik.Web.UI” is undefined

Cause:

As the website denies access to all pages to unauthorized users, access to the Telerik.Web.UI.WebResource.axd handler is unauthorized. This causes the handler to serve the content of the login page instead of the combined scripts, hence the error.

Suggested solution:

Add a <location> section to the application configuration file to allow access to Telerik.Web.UI.WebResource.axd to all users, like:

[web.config] Add location property

<configuration>
...
<location path="Telerik.Web.UI.WebResource.axd">
   <system.web>
     <authorization>
       <allow users="*"/>
     </authorization>
   </system.web>
 </location>
...
</configuration>

Let me know whether this solution helps.

Regards,
Martin
the Telerik team

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[Alberto]

Thank you, this fix my issue. I'm using forms authentication and with this lines the error "ASP.NET Ajax client-side framework failed to load" disappear.

[Darrel]

Thank you. Solved my issue in a VS 2022 ASP.NET project. I was getting this error when debugging in VS 2022.

[Jerry Jansen]

Thanks Martin but that is not the problem.

I have found the problem and it is that the new version (1314.35) in NOT compatible with Intelligencia.UrlRewriter.dll!

Version 1208.35 is compatible and I need Intelligencia.UrlRewriter.dll

[Chris Winters]

I recently moved from a .net 2.5 to a .net 3.5 solution and I am getting these same errors:

if (typeof(Sys) === 'undefined') throw new Error('ASP.NET Ajax client-side framework failed to load.');


i am racking my brain trying to find the solution, but nothing outlined here works.

[Vlad]

Hi,

You will need to change your Web.config - check this thread for more info:
http://forums.asp.net/p/1207960/3567155.aspx

Sincerely yours,
Vlad
the Telerik team

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[Chris Winters]

None of the recommendations in this article resolve my issue.

My issue is specifically the RadScriptManager returning the "

ASP.NET Ajax client-side framework failed to load

" error message.

[Daniel]

Hello Chris,

I'm afraid there are a number of different reasons for this error. I would really appreciate it if you could provide a working project that demonstrate the problem.

In the meantime you can examine the following threads:
RadScriptManager not woirking with login screen - Ajax Forum - ASP ...
Microsoft JScript runtime error: Sys.ScriptLoadFailedException ...
RadScriptManager Causes "ASP.NET Ajax client-side framework failed ...

Best regards,
Daniel
the Telerik team

Instantly find answers to your questions on the new Telerik Support Portal.
Watch a video on how to optimize your support resource searches and check out more tips on the blogs.

[Cesar Perez]

I'm having the same issue after I downloaded the Service Pack 2 of the Telerik controls last night.

I need to resolve this issue.

Thanks,
jc

[Daniel]

Hello Cesar,

Unfortunately there is no universal remedy for this error. I will gladly debug your code locally provided that you can isolate the problem in a runnable sample.

Thank you for your understanding.

Best regards,
Daniel
the Telerik team

[Dayre-Musetti]

I've got exact same problem. Adding a location path in web.config as desribed by martin solve it. Thank's

[Pieter]

I've got exact same problem. Adding a location path in web.config as desribed by martin solved it. Did not realize it until I reloaded my browser! Thank's

[DeNuwe]

I get this problem since I downloaded UI for ASP.NET AJAX v2014.3.1002.45. I tried the <location> but it did not work for me. My app has been working since April and now it is not working any more. I need URGENT assistance please!

[Daniel]

Hello DeNuwe,

I'm afraid there are various reasons that may cause such an error, ranging from JS errors to permission issues as stated below. This is why the fastest way to help you resolve the problem would be to ask you to provide a runnable demo which I could debug on my end. I would recommend that you submit a support ticket with the aforementioned example attached.

Regards,
Daniel
Telerik

 

 

[Tomislav]

Hi,

to me problem solver was -

<telerik:RadScriptManager runat="server"   EnablePageMethods="True" EnableScriptCombine="false"  ></telerik:RadScriptManager>

EnableScriptCombine="false" - should be false, since telerik handler cannot combine scripts(2013.3.1324.40 version).

[Sabitri]

Thanks Tomislav. It is great help. I have tried all dll/reference and config changes but it was still not working. Seems they were upto mark. The EnableScriptCombine false resolved my issue too.
The issue was coming after we moved 3.5 framework to 4.5 and used VisualStudio 2013.

Again thanks a lot for giving the solution :)

[Jose]

Thanks Tomislav.
Setting EnableScriptCombine false resolved my issue too.
The issue was coming after I moved 3.5 framework to 4.5 and used VisualStudio 2012.

[Sravani]

Hi,

We are migrating the project from .Net 4.0 framework, IIS6, VS2010 to .Net 4.5 framework,IIS8 & VS 2013. We are getting "ASP.NET Ajax client-side framework failed to load." exception. In our older code we are using telerik version 2011.1.413.35. After running the same code using 4.5 and when we are accessing the page, telerik itself is not loaded in scripts whereas all other scripts are loading.

We tried all the solutions given above. Still none of the solutions helped me.

Should I need to change the telerik version. If yes, what is the version I should use?

Please help us in this issue.

With Regards,
Sravani.

[Marin Bratanov]

Hello Sravani,

Can you confirm you have all the required HTTP handlers in the web.config: http://docs.telerik.com/devtools/aspnet-ajax/general-information/web-config-settings-overview#mandatory-additions-to-the-webconfig?

It is also important that this server has the MS AJAX framework installed, as noted here: http://docs.telerik.com/devtools/aspnet-ajax/deployment/deploying-a-telerik-enabled-webapplication.

The next thing is to ensure all the requests for them can pass, which often involves adding the appropriate location elements and excluding them from any routing that is used.

Since you are using VS2013, I also advise that you disable the BrowserLink feature as it is known to cause issues with webresources requests.

Considering the upgrade to .NET 4.5, it is best to also use builds of our assemblies that target .NET 4.5, but they are available in later versions. Since the 2011 version you are using does not support the current browsers, I would strongly advise that you update to the latest (2015.1.401.45 at the time of writing).

Regards,

Marin Bratanov
Telerik

[John]

That worked!  I don't why it worked; but, it worked.  With no changes to my code, all I did was upgrade from 2014 Q3 to 2015 Q2, and I got the 'ASP.NET Ajax client-side framework failed to load'.  Once I added the 'Location Path...'  and 'Allow Users' tag, it worked.  Thanks, Martin.

[SureshKumar]

I did the above steps still getting same issue.

ASP.NET Ajax client-side framework failed to load
'Sys' is undefined
“Telerik.Web.UI” is undefined

My Config settings

<assemblies>
<add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
<add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
</assemblies>

<httpHandlers>
<add path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" validate="false"/>
<add path="Telerik.RadUploadProgressHandler.ashx" type="Telerik.Web.UI.RadUploadProgressHandler" verb="*" validate="false"/>
</httpHandlers>
<httpModules>
<add name="RadUploadModule" type="Telerik.Web.UI.RadUploadHttpModule, Telerik.Web.UI"/>
</httpModules>

<handlers>
<add path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" name="Telerik.Web.UI.WebResource"/>
<add path="Telerik.RadUploadProgressHandler.ashx" type="Telerik.Web.UI.RadUploadProgressHandler" verb="*" name="Telerik.Web.UI.RadUploadProgressHandler"/>
</handlers>

 

Let me what i am missing.

 

[SureshKumar]

This i have deployed in new windows server 2012 server.

[Marin Bratanov]

Hi,

You need to make sure the MS AJAX framework functions properly on the server, as described in the prerequisites section: http://docs.telerik.com/devtools/aspnet-ajax/general-information/adding-the-telerik-controls-to-your-project.

Once an app with a simple asp:ScriptManager and asp:UpdatePanel works fine, loads all its resources and performs partial postbacks, our controls should work too. If you have some form of authentication enabled, you may need to allow access to our handlers via <location> elements.

Regards,

Marin Bratanov
Telerik by Progress

[ana]

I am having the same issue as the first one mentioned in this link. We are using telerik and Intelligencia.UrlRewriter. All other ajax calls work,except where they are being rewritten. Jerry Jansen- I know this is old but do you remember what the solution was for your issue?

[SSirica]

Thanks, that did it for me!