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 license key is detected	TKL002	Install a license key to activate the UI components and remove the error message.
Invalid license key	TKL003	Download a new license key and install it to activate the UI components and remove the error message.
Your subscription license has expired.	TKL103; TKL104	Renew your subscription and download a new license key.
Your perpetual license is invalid.	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 trial license has expired.	TKL105	Purchase a commercial license to continue using the product.
Your license is not valid for the detected product(s).	TKL101	Review the purchase options for the listed products. Alternatively, remove the references to the listed packages from package.json.