Unknown JSON DataSource Transport Type Warning Occurs

Updated on Dec 10, 2025

Environment

Product	Progress® Kendo UI® for jQuery
Kendo Version	2017.2.621

Description 

A warning of an unknown JSON DataSource transport type occurs.

Cause

The possible causes of the issue may be either of the following:

• Invalid Kendo UI DataSource type configuration is set. For example:

  js

  dataSource: {
    type: "json"
  }

• A JavaScript file is missing when using a DataSource type that is not included in kendo.all.min.js. For example, aspnetmvc-ajax, jsdo, and others. Specifically, json is not a valid DataSource type and it does not require a separate JavaScript file.

Error Message

Unknown DataSource transport type json

Solution

Use a valid type value, or remove the type property, or add the corresponding missing file—for example, kendo.aspnetmvc.min.js when using the Kendo UI MVC wrappers.

Note that the dataSource type differs from the type of the transport actions.