[c#] WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for jquery

In my web application I get the following error:

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

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for 'jquery'. Please add a ScriptResourceMapping named jquery(case-sensitive).

How can I solve it?

Jaqen H'ghar is spot-on. A third way is to:

1. Go to Manage NuGet Packages
2. Install Microsoft.jQuery.Unobtrusive.Validation
3. Open Global.asax.cs file and add this code inside the Application_Start method

Code that runs on application startup:

ScriptManager.ScriptResourceMapping.AddDefinition("jquery", new ScriptResourceDefinition {
    Path = "~/Scripts/jquery.validate.unobtrusive.min.js",
    DebugPath = "~/Scripts/jquery.validate.unobtrusive.min.js"
});

Further to the accepted answer, I ran into issues with code elsewhere on my site requiring jQuery along with the Migrate Plugin.

When the required mapping is added to Global.asax, when loading a page requiring unobtrusive validation (for example a page with the ChangePassword ASP control), the mapped script resource conflicts with the already-loaded jQuery and migrate scripts.

Adding the migrate plugin as a second mapping solves the issue:

// required for UnobtrusiveValidationMode introduced since ASP.NET 4.5
var jQueryScriptDefinition = new ScriptResourceDefinition
{
    Path = "~/Plugins/Common/jquery-3.3.1.min.js", DebugPath = "~/Plugins/Common/jquery-3.3.1.js", LoadSuccessExpression = "typeof(window.jQuery) !== 'undefined'"
};
var jQueryMigrateScriptDefinition = new ScriptResourceDefinition
{
    Path = "~/Plugins/Common/jquery-migrate-3.0.1.min.js", DebugPath = "~/Plugins/Common/jquery-migrate-3.0.1.js", LoadSuccessExpression = "typeof(window.jQuery) !== 'undefined'"
};
ScriptManager.ScriptResourceMapping.AddDefinition("jquery", jQueryScriptDefinition);
ScriptManager.ScriptResourceMapping.AddDefinition("jquery", jQueryMigrateScriptDefinition);

To fix this problem on specific page need to set some validation settings when page loading. Write code below in Page_Load() method:

protected void Page_Load(object sender, EventArgs e)
    {
        ValidationSettings.UnobtrusiveValidationMode = UnobtrusiveValidationMode.None;
    }

Its work for me in .NET 4.5

Right click on your website go to property pages and check both the check-boxes under Accessibility validation click on ok. run the website.

The exception indicates a problem with the unobtrusive JavaScript validation mode. This issue is not Sitefinity specific and occurs in any standard ASP.NET applications when the project targets .NET 4.5 framework and the pre-4.5 validation is not enabled in the web.config file.

Open the web.config file and make sure that there is a ValidationSettings:UnobtrusiveValidationMode in the app settings:

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

I think this is the best solution for this type error. So please add below line. Also it work my code when I am using MSVS 2015.

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