# License Activation Errors and Warnings
Using Kendo UI for Angular 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.
## 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 an expired trial license.
* A missing license for Kendo UI for Angular.
* Not [installing a license key](https://www.telerik.com/kendo-angular-ui-develop/components/licensing#install-or-update-the-license-key-file-in-your-project) in your application.
* Not [updating the license key](https://www.telerik.com/kendo-angular-ui-develop/components/licensing#install-or-update-the-license-key-file-in-your-project) after renewing your Kendo UI for Angular license.
* Cached old (expired) license key.
## License Warnings
If you use Kendo UI for Angular in a project with an expired or missing license, the UI components exhibit the following invalid license attributes:
* A [watermark](https://www.telerik.com/kendo-angular-ui-develop/components/licensing/license-errors-and-warnings#watermark) appears over a number of selected components.
* A [banner](https://www.telerik.com/kendo-angular-ui-develop/components/licensing/license-errors-and-warnings#banner) is rendered on pages that use the Kendo UI for Angular components.
* A [warning message](https://www.telerik.com/kendo-angular-ui-develop/components/licensing/license-errors-and-warnings#console-warning) is logged in the browser console of pages rendering the Kendo UI for Angular components.
### Watermark
A watermark appearing in the `Light Theme` mode:
A watermark appearing in the `Dark Theme` mode:
### Banner
A banner with an action button appears on pages that use Kendo UI for Angular components when the license is invalid, expired, or missing:
* Clicking the action button redirects you to start a trial, purchase, or renew your license, depending on your license status.
* Clicking the **x** button of the banner closes it until the page is reloaded or a license is activated.
### Console Warning
A warning message similar to the following is logged in the browser's console:
## License Activation Errors
If you use Kendo UI for Angular in a project with an expired or missing license, [the `kendo-ui-license activate` command](https://www.telerik.com/kendo-angular-ui-develop/components/licensing#install-or-update-the-license-key-file-in-your-project) will indicate the following errors or conditions:
| Error or Condition | Message Code | Solution |
| ----------------------------------------------------------------- | ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `No Telerik or Kendo UI product references detected in project` | `TKL001` | - If you use Telerik products and see this message, update the `@progress/kendo-licensing` package to version 1.4.9 or later.
- If you do not use Telerik products, remove the Telerik.Licensing NuGet reference from your project. |
| `No Telerik and Kendo UI License file found` | `TKL002` | [Install a license key](https://www.telerik.com/kendo-angular-ui-develop/components/licensing) to activate the UI components and remove the error message. |
| `Corrupted Telerik and Kendo UI License Key content` | `TKL003` | License key has been automatically truncated due to size limits. Check this [FAQ](https://www.telerik.com/kendo-angular-ui-develop/components/licensing/faq#why-is-my-license-key-truncated-when-an-environment-variable-is-set-on-windows) to remove the error message. |
| `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](https://www.telerik.com/kendo-angular-ui-develop/components/licensing#install-or-update-the-license-key-file-in-your-project). |
| `Kendo UI for Angular 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](https://www.telerik.com/kendo-angular-ui-develop/components/licensing#download-your-license-key-file).
- 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](https://www.telerik.com/kendo-angular-ui-develop/components/licensing##download-your-license-key-file). |
| `Your trial expired` | `TKL105` | Purchase a commercial license to continue using the product. |
## See Also
* [Setting Up Your License Key](https://www.telerik.com/kendo-angular-ui-develop/components/licensing)
* [Adding Deployment Keys to CI/CD Services](https://www.telerik.com/kendo-angular-ui-develop/components/licensing/ci-services)
* [Frequently Asked Questions](https://www.telerik.com/kendo-angular-ui-develop/components/licensing/faq)