I was using Visual Studio 2012 and I created an empty ASP.Net Web Application, when I tried to add the traditional validator controls to a new page, this error occurs:
WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for 'jquery'. Please add a ScriptResourceMapping named jquery(case-sensitive).
It was complaining about the ValidationSettings:UnobtrusiveValidationMode value. To Disable it you need to do the following in the web.config file.
<add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />