AJAX Error: 'Sys' is undefined

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May 7 2007

.NET

If you are using AJAX enabled web site or project, you may come across this error message. I got this error message too and spent few hours to fix this problem. I tried finding all possible solutions on Google and finally concluded with following three steps.

- Web.Config: Make sure your web.config is correctly configured to handle AJAX enabled request. You might have created a project which was not AJAX enabled earlier and now you want to Ajaxfy. The best solution is creating a new project ASP.NET AJAX Enabled Web Site. It will create a Web.config file by default. Compare this Web.config file with your other project’s Web.config file which is casuing the error. Make sure that you are not missing any new section. You can simply copy and paste it at appropriate place. For detail information you can also visit at http://ajax.asp.net/docs/configuringASPNETAJAX.Aspx
- Using Master Page: If your ASP.NET web page is using a Master Page, make sure your Script Manager Control is placed in Master Page only. Content page should not be using Script Manager Control.
- Regular Web Page: If you are not using a Master Page then each ASP.NET web page must have its own Script Manager Control.

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Comments

7/6/2007 1:48:20 AM #

Thanks a lot, pyaare Vishamohan. Your article was the only way I could solve this Sys not defined bug. Thanks again. & keep posting such queer bug-fixes. They help a lot!
Anand

Anand

9/20/2007 5:57:30 PM #

Hi,

Thanks a lot. Its very helpful.

Anju

2/3/2008 10:56:13 PM #

Wonderful post! I have been piling through blog after blog and posting everywhere I know and have not been able to resolve this error.

"If your ASP.NET web page is using a Master Page, make sure your Script Manager Control is placed in Master Page only. Content page should not be using Script Manager Control."

Brilliant!!!! Thank you!

Ryan

3/2/2008 5:22:16 PM #

Hi dear

The above define 3 option is very right, I was fcing a javascript problem "Sys Undifine" then i did follow your 1st point and modify my Web config and my problem got solve.

Thank's

Anil Soni

5/22/2008 3:20:09 PM #

Hi Vishwa, I have tried it all but still can't get it to work !!! I have copied the Web.Config from the AjaxEnabled website but still I can't get rid of this DUMB ERROR

Ammar

7/25/2008 11:01:07 PM #

Thank you your tip on creating a correct AJAX web.config saved me a lot of time

Chris

8/25/2008 5:24:22 AM #

Excellent!! Thanks Man.!!

Dil

9/6/2009 11:39:53 PM #

Admiring the time and effort you put into your blog and detailed information you offer!

Internet marketing

9/17/2009 9:28:23 AM #

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Orlando A

9/19/2009 5:04:57 PM #

Nice information, many thanks to the author. It is incomprehensible to me now, but in general, the usefulness and significance is overwhelming. Thanks again and good luck!

Orlando A

10/2/2009 6:43:39 AM #