License Activation Errors and Warnings

Starting with the 2025 Q1 release, using Telerik UI for WPF without a license or with an invalid license causes specific license warnings and errors. This article defines what an invalid license is, explains what is causing it, and describes the related license warnings and errors.

A missing, expired, or invalid license will result in:

• A watermark appearing on application startup.

• A modal dialog appearing on application startup. Clicking the OK button of the dialog closes the dialog and removes the banner until the next application startup.

  

• A warning message similar to the following appearing in the build log:

  

  

Invalid License

An invalid license can be caused by any of the following:

• Using an expired subscription license—subscription licenses expire at the end of the subscription term.

• Using a perpetual license for product versions released outside the validity period of your license.

• Using an expired trial license.

• A missing license for Telerik UI for WPF.

• Not installing a license key in your application.

• Not updating the license key after renewing your Telerik UI for WPF license.

License Warnings and Errors

When using Telerik UI for WPF in a project with an expired or missing license, the Telerik.Licensing build task will indicate the following errors or conditions:

Condition or Error	Message Code	Solution
No Telerik and Kendo UI License file found	TKL002	Install a license key to activate the UI components and remove the error message.
Corrupted Telerik and Kendo UI License Key content in: [file path or environment variable name]	TKL003	If you use a telerik-license.txt file to activate the components, download a new license key file and place it in your home directory. Make sure to use a license key and not a script key. If you use the TELERIK_LICENSE environment variable to store your license key, download a new license key, update the content of the environment variable, and make sure it contains the entire key.
Unable to locate licenses for all products	TKL004	Your license is not valid for all Telerik and Kendo products added to your project. If you have already purchased the required license, then update your license key.
Telerik UI for WPF is not listed in your current license file	TKL101	Review the purchase options for the listed products. Alternatively, remove the references to the listed packages from package.json.
Your current license has expired	TKL102	You are using a product version released outside the validity period of your perpetual license. To remove the error message, do either of the following: Renew your subscription and download a new license key. Downgrade to a product version included in your perpetual license as indicated in the message.
Your subscription license has expired	TKL103; TKL104	Renew your subscription and download a new license key.
Your trial license has expired	TKL105	Purchase a commercial license to continue using the product.
No Telerik or Kendo UI product references detected in project	TKL001	If you use Telerik products and see this message, update the Telerik.Licensing package to version 1.4.6 or later. If you do not use Telerik products, remove the Telerik.Licensing NuGet reference from your project.

See Also

• Setting Up Your License Key
• Frequently Asked Questions about Your UI for WPF License Key
• Adding the License Key to CI Services