WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for 'jquery'. Please add a ScriptResourceMapping named jquery(case-sensitive)

You need a web.config key to enable the pre 4.5 validation mode.

More Info on ValidationSettings:UnobtrusiveValidationMode:

Specifies how ASP.NET globally enables the built-in validator controls to use unobtrusive JavaScript for client-side validation logic.

Type: UnobtrusiveValidationMode

Default value: None

Remarks: If this key value is set to "None" [default], the ASP.NET application will use the pre-4.5 behavior (JavaScript inline in the pages) for client-side validation logic. If this key value is set to "WebForms", ASP.NET uses HTML5 data-attributes and late bound JavaScript from an added script reference for client-side validation logic.

Example:

    <appSettings>
      <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />
    </appSettings>

Rather than disabling a new feature, I opted to follow the instructions of the error. In my global.asax.cs I added:

protected void Application_Start(object sender, EventArgs e)
{
    string JQueryVer = "1.7.1";
    ScriptManager.ScriptResourceMapping.AddDefinition("jquery", new ScriptResourceDefinition
    {
        Path = "~/Scripts/jquery-" + JQueryVer + ".min.js",
        DebugPath = "~/Scripts/jquery-" + JQueryVer + ".js",
        CdnPath = "http://ajax.aspnetcdn.com/ajax/jQuery/jquery-" + JQueryVer + ".min.js",
        CdnDebugPath = "http://ajax.aspnetcdn.com/ajax/jQuery/jquery-" + JQueryVer + ".js",
        CdnSupportsSecureConnection = true,
        LoadSuccessExpression = "window.jQuery"
    });
}

This comes from an msdn blog post which highlights some of the advantages of script resource mappings. Of particular interest to me was centralized control over the delivery of the script files based on "debug=true", EnableCDN, etc.

There are at least three ways to disable the use of unobtrusive JavaScript for client-side validation:

1. Add the following to the web.config file:

   <configuration>
     <appSettings>
       <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />
     </appSettings>
   </configuration>

2. Set the value of the System.Web.UI.ValidationSettings.UnobtrusiveValidationMode static property to System.Web.UI.UnobtrusiveValidationMode.None
3. Set the value of the System.Web.UI.Page.UnobtrusiveValidationMode instance property to System.Web.UI.UnobtrusiveValidationMode.None

To disable the functionality on a per page basis, I prefer to set the Page.UnobtrusiveValidationMode property using the page directive:

<%@ Page Language="C#" UnobtrusiveValidationMode="None" %>