Thursday, September 22, 2011

There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined

Last time I got the following error:
HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid.
See in the image below the following config error, and also watch the config source.
There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined
Root of the error
I got the error when I was deploying a web application precompiled in 2.0 onto the production server with 4.0. The simple search reveals that it is known issues with VS 2010 and 2.0. But my site is 2.0 enabled. What's the root of the error then?  
My conclusion (and please correct me if necessary) I have configured web extension namespaces in my web.config file. You don't see this in 3.5 and 4.0 enabled sites since servers with asp,net 3.5/4.0 by default server ajax services. But 2.0 has to be ajax enabled by installing ajax extension 1.0 which you can download from here. Sensed duplicate entry of system.web.extension section group? Yes, don't include the following section group in the config section if your site runs on 2.0 but published on 3.5/4.0.

Comment out the config section (or remove it if you like), and you are done. Good luck! kick it on


Anonymous said...

Many Thanks. It helped a lot

Anonymous said...

I have built my site in 3.5 and also have the same error when deploying it.
I could't find duplicate's.

Anonymous said...

my errors-
Error Code 0x800700b7
Config Error There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined


Anonymous said...

web.config file...

Anonymous said...

my config file-

Dilip Nikam said...


I also face the same problem while creating the new application.

After digging into the error i found the solution which is regarding to the .Net Framework version of the application pool of the created for new web application.

Some how the application pool defaults set to v4.0 instead of v2.0. So i have updated the same with v2.0 and created application again.

For more details please have look of the link []

Wilson Contreras said...

Thanks a lot, removing .. solved my problem.

Anonymous said...

thanks. that made my day...

Unknown said...

Just change the target framework of project to .NetFramework4.
Recompile and Publish it. Problem will be resolved.

Anonymous said...

Thanks for the post!

I got the above error after installing a v4.0 website on my box (they had all been v2.0 before that.)

When I installed the v4.0 site originally, I received the message in the link below, and took the recommended steps in the discussion to fix it:

..after following the instructions and running aspnet_regiis -iru, my v2.0 site stopped working. That's because its AppPool in IIS had been set to v4.0 during the original fix. Setting that AppPool back to v2.0 fixed the problem.

Anonymous said...

Worked for me!

Smokepk said...

Simply switch the application pool.

Anonymous said...

Worked for me in Window 8 with IIS 8.0. Many thanks for saving me lots of time!

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