# Activation Errors and Warnings
Starting with the 2025 Q1 release, Telerik Document Processing reports licensing problems through build messages and runtime indicators. This article explains invalid licenses, distinguishes build-time messages from runtime behavior, and describes the related warning and error codes.
The result depends on the license type and whether you build or run the application:
* During a build, `Telerik.Licensing` reports a warning or error when it cannot validate the license.
* At runtime, a missing or invalid trial license can prevent normal operation and display a watermark and modal dialog box.
* An expired perpetual license can continue to work in a deployed application. Rebuilding with a product version outside the license validity period produces licensing indicators.
* An expired subscription license can continue to work in a deployed application. Rebuilding the application produces licensing indicators.
Click the **OK** button in the modal dialog box to close it and remove the banner until the next application startup.
## 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 the product.
* Not installing a license key in your application.
* Not updating the license key after renewing your product license.
## License Warnings and Errors
When you use the product in a project with an expired or missing license, the `Telerik.Licensing` build task reports the following conditions:
| **Condition or message** | **Code** | **Resolution** |
| ---------------------------------------------------------------------------------------------------------------------------------------- | -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `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 1.4.9 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/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-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](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-license-key) 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](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-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](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-license-key). |
| `"Telerik Document Processing Libraries" product 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 the project file (`.csproj`). |
| `Your current license has expired.` | TKL102 | Use a license that covers the product version. [Download a new license key](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-license-key#downloading-the-license-key) after renewing, or downgrade 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/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-license-key). |
| `Your trial license has expired.` | TKL105 | Purchase a commercial license to continue using the product. |
| `Services associated with Telerik Document Processing Libraries require a subscription or trial license. Obtain a subscription license.` | TKL403 | In Q1 2026, this warning can occur when `Telerik.UI.for.Wpf.AllControls` or `UI.for.WinForms.AllControls` adds Telerik Document Processing Agent Tools. Replace the combined package with individual packages if you do not use the tools. Otherwise, purchase a subscription license. See [Resolving the TKL403 Licensing Warning](https://www.telerik.com/document-processing-libraries/documentation/knowledge-base/tkl403-warning-telerik-document-processing). |
## See Also
* [Setting Up Your License Key](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/setting-up-license-key)
* [Adding the License Key to CI Services](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/adding-license-key-ci-cd-services)
* [License Key FAQ](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-key/frequently-asked-questions)
* [License Agreement](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/license-agreement)
* [Redistributing Telerik Document Processing](https://www.telerik.com/document-processing-libraries/documentation/distribution-and-licensing/redistributing-telerik-document-processing)
* [Unable to find package Telerik.Licensing](https://www.telerik.com/document-processing-libraries/documentation/knowledge-base/dpl-package-update-failure-license)
* [Handling License Key File Name and Environment Variable Name Changes in the 2025 Q1 Release](https://www.telerik.com/document-processing-libraries/documentation/knowledge-base/handling-license-file-name-changes)
* [Telerik.Licensing NuGet package is not available on the Telerik NuGet feed](https://www.telerik.com/document-processing-libraries/documentation/knowledge-base/dpl-telerik-licensing-nuget-feed)
* [Resolving TKL403 Licensing Warning for Telerik Document Processing](https://www.telerik.com/document-processing-libraries/documentation/knowledge-base/tkl403-warning-telerik-document-processing)