Configure IronXL License in web.config (C#)

Curtis Chau

Updated: May 9, 2026

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  # Configure IronXL License in web.config (C&#35;) <i class="fa-regular fa-circle-check" style="color: #63E6BE;"></i> The problem has been **resolved** as of IronXL version [2024.3.20](https://www.nuget.org/packages/IronXL.Excel/2024.3.20). ```txt Exception: Unhandled exception. IronSoftware.Exceptions.LicensingException: IronXL must be licensed for development. ``` For older IronXL versions, specifically those between versions [2023.4.13](https://www.nuget.org/packages/IronXL.Excel/2023.4.13) and [2024.3.20](https://www.nuget.org/packages/IronXL.Excel/2024.3.20), there is a known licensing issue in: - **ASP.NET** projects - **.NET Framework version >= 4.6.2** The key stored in a `Web.config` file will **NOT** be picked up and used by the product. ## Workaround To address this issue, it is recommended to retrieve the license key from the `Web.config` file using **ConfigurationManager** in the code, and then apply it to the `License.LicenseKey` property. **Example:** Below is an example of how to store the license key in a `Web.config` file: ```xml <configuration> ... <appSettings> <add key="IronXL.LicenseKey" value="IronXL-MYLICENSE-KEY-1EF01"/> </appSettings> ... </configuration> ``` With the above XML file setup, we can use **ConfigurationManager** to retrieve the license key value and set it to the `IronXL.License.LicenseKey` property: ```csharp using System.Configuration; // Retrieve the license key from the Web.config appSettings section string licenseKey = ConfigurationManager.AppSettings["IronXL.LicenseKey"]; // Apply the retrieved license key to the IronXL component IronXL.License.LicenseKey = licenseKey; ``` In this example, the `ConfigurationManager.AppSettings` is used to retrieve the value of `IronXL.LicenseKey` from `Web.config`. The retrieved license key is then set to the `IronXL.License.LicenseKey` to ensure that the IronXL components can function properly.

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The problem has been resolved as of IronXL version 2024.3.20.

Exception: Unhandled exception. IronSoftware.Exceptions.LicensingException: IronXL must be licensed for development.

Exception: Unhandled exception. IronSoftware.Exceptions.LicensingException: IronXL must be licensed for development.

For older IronXL versions, specifically those between versions 2023.4.13 and 2024.3.20, there is a known licensing issue in:

• ASP.NET projects
• .NET Framework version >= 4.6.2

The key stored in a Web.config file will NOT be picked up and used by the product.

Workaround

To address this issue, it is recommended to retrieve the license key from the Web.config file using ConfigurationManager in the code, and then apply it to the License.LicenseKey property.

Example:

Below is an example of how to store the license key in a Web.config file:

<configuration>
  ...
  <appSettings>
    <add key="IronXL.LicenseKey" value="IronXL-MYLICENSE-KEY-1EF01"/>
  </appSettings>
  ...
</configuration>

<configuration>
  ...
  <appSettings>
    <add key="IronXL.LicenseKey" value="IronXL-MYLICENSE-KEY-1EF01"/>
  </appSettings>
  ...
</configuration>

With the above XML file setup, we can use ConfigurationManager to retrieve the license key value and set it to the IronXL.License.LicenseKey property:

using System.Configuration;

// Retrieve the license key from the Web.config appSettings section
string licenseKey = ConfigurationManager.AppSettings["IronXL.LicenseKey"];
        
// Apply the retrieved license key to the IronXL component
IronXL.License.LicenseKey = licenseKey;

using System.Configuration;

// Retrieve the license key from the Web.config appSettings section
string licenseKey = ConfigurationManager.AppSettings["IronXL.LicenseKey"];
        
// Apply the retrieved license key to the IronXL component
IronXL.License.LicenseKey = licenseKey;

Imports System.Configuration

' Retrieve the license key from the Web.config appSettings section
Dim licenseKey As String = ConfigurationManager.AppSettings("IronXL.LicenseKey")

' Apply the retrieved license key to the IronXL component
IronXL.License.LicenseKey = licenseKey

Imports System.Configuration

' Retrieve the license key from the Web.config appSettings section
Dim licenseKey As String = ConfigurationManager.AppSettings("IronXL.LicenseKey")

' Apply the retrieved license key to the IronXL component
IronXL.License.LicenseKey = licenseKey

In this example, the ConfigurationManager.AppSettings is used to retrieve the value of IronXL.LicenseKey from Web.config. The retrieved license key is then set to the IronXL.License.LicenseKey to ensure that the IronXL components can function properly.

Curtis Chau

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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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