ASP.NET Ajax client-side framework failed to load

I got this error:

ASP.NET Ajax client-side framework failed to load

with the error:

‘Sys’ is undefined.

The error qppears in IE on the bottom (error message), and appears only when i’m running the site on server. on my localhost everything works fine.

i moved for new server, and there i have the problem. in my previous server everything was fine.

The problem comes from the SCRIPTMANAGER of the ajax.

what i can to do? somthing in the web.config, or should the host company need to install somthing?

ASP.NET 4, IIS 7.5

The ugly yellow triangle on the IE is not what is disturbing me.. the big problem is that the script manager with the update pannel – dont work !

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

A quick solution is to update your web.config and add following section

<handlers>
    <remove name="WebServiceHandlerFactory-Integrated"/>
    <remove name="ScriptHandlerFactory"/>
    <remove name="ScriptHandlerFactoryAppServices"/>
    <remove name="ScriptResource"/>
    <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
    <add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
    <add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
</handlers>

Method 2

I had faced the same issue and the culprit was a web.config file from some other app, that was kept on the web root. (Someone had installed the app on web root)
Once it was moved inside a folder, the problem disappeared.

Method 3

I had the same error and, after a lot of head-scratching, I discovered that the custom HttpModule that I had created was intercepting all Http Requests and wasn’t limited to .aspx requests only.

My module evaluated some criteria and redirected to a 404 or 500 page where necessary. The problem was that it was doing this for all requests including the requests for .axd resources such as the ScriptManager.axd. By filtering for .aspx files in the module, it all magically began to work again.

Sometimes it’s the things right under your nose that are the problem. I hope that this helps some poor sole and saves them the time and effort it took me.

Cheers,

Kaine

Method 4

Just for reference purposes, after hunting down this error for two days, we finally found the reason. It was completely different than the other ones stated here.

The effective reason was an erroneous entry in the “Web.config” file. It was this line:

<httpRedirect 
    enabled="true" 
    destination="https://some-domain-of-me.com" 
    exactDestination="false"  
    childOnly="true" />

The whole website worked correctly, except that the ASP.NET Ajax stuff did not load.

Using Firefox and the network log in the web developer console, I saw a huge amount of the same 302 HTTP redirects of some .AXD files. I.e. there was an endless loop which the browser finally killed after approx. 20-30 redirects.

The above line caused these redirects.

My assumption is this behavior:

1. There was an endless redirect for the ASP.NET Ajax .AXD files.
2. The browser tried to load it several times.
3. The browser finally gave up loading of the files.
4. This caused the above error message to be printed:

ASP.NET Ajax client-side framework failed to load

The solution was to remove the (unnecessary) redirect. After this, everything worked fine, again.

(We did the actual redirects we needed then by installing the IIS URL Rewrite module)

Method 5

I had the same error for past two days. finally i resolve the issue.
add the following items in Managed Handler in IIS.

*.asmx

System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35

ScriptHandlerFactory

*_AppService.axd

System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35

ScriptHandlerFactoryAppServices

ScriptResource.axd

System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35

ScriptResource

Method 6

Turns out the solution for me was to remove URL rewrites from the application’s site! Most of our site is WordPress static pages, which needed the rewrites; when we converted the application to a site, IIS automatically applied the rewrites.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0