I have a web application that was working fine. I added the tab control from the Ajax control toolkit and I start getting the error
0x800a138f - JavaScript runtime error: Unable to get property 'length' of undefined or null reference
To simplify it, using all the latest (Visual Studio Ultimate 2013, IE 11, .NET 4.5, Ajax Control Toolkit 15.1)...
Start a new ASP.NET web application project with C# code behind. In the front page, put a button and an AJAX update panel. Inside the update panel, put an AJAX toolkit Tab Control. Just to have something, add the text "hello" inside the first (and only) tab of the tab control.
Now, on the button you added, on it's click event, tell the update panel to update itself.
panel1.update();
run the project and click on the button, and you will get the error.
Similarly, if you don't use an update panel, but just put an asp label in the tab control, and in the button click event you change the text of the label, that also causes the error. It appears that any programmatic change to the tab panel is causing this error.
Any ideas? please!
This is a bug in the Ajax Control toolkit which only occurs in IE. I logged it in DevExpress' Codeplex page for the toolkit and they replied that this is indeed a bug that is fixed and the fix will be out in the next release.