I suddenly got a problem and trying very hard to get rid off it but no success.
The problem is that: one day when i opened my website project in VS2005, i was shocked to see the red lines under most of the Controls in html source file. They were working fine before but this time when i placed the mouse pointer over one of the red-underlined control, a tooltip appears with the following error:
"Element 'TextBox' is not a known Element.This can occur if there is a compilation error in the web site."
I am attaching the screenshot image of this error. plz download it and see what i am trying to say.
After some Headache, i realized that this TextBox is placed inside an UpdatePanel. Then I did the following Series of actions:
1- I created a new website in vs2005, to check if the "Ajax" is working or not.
2- I placed one TextBox on webpage. Fine. No error. No red-underline.
3- I placed one UpdatePanel from the "Ajax Extension Toolbox" but a red line appears under the UpdatePanel Declaration showing the same tooltip:
"Element 'UpdatePanel' is not a known Element.This can occur if there is a compilation error in the web site."
4- Then i drag and dropped that TextBox inside the UpdatePanel Tags, the TextBox became red-underlined.
5- It means there was something wrong with the AJAX. so I uninstalled the Ajax Extension 1.0 and downloaded it again from asp.net web site.
6- After Re-Installing the Ajax Extension, I added the Reference of AjaxControlToolkit. dll from the bin directory of the sample website.
but still the compliler is not recognizing the UpdatePanel and the controls inside it.
I m Helpless.
Please Help.
Mansoor Bari
Shijo BabyPosted Sep 9, 2010, 9:19 AM
Mansoor BariPosted Aug 11, 2008, 6:20 AM
Thanks a lot MANISH.
I changed the TagPrefix from asp to AJAX and it resolved the issue.
I discussed this problem to so many peoples on so many forums and blogs but You are the first person who provided the correct solution. Thanks
Blocked AccountPosted Aug 11, 2008, 5:50 AM
Go into your web.config file and change the tag-prefix naming for the ASP.NET AJAX controls to something other than
For example, instead of:
change them to something like this:
<add tagPrefix="ajax" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>