---
title: "Troubleshooting applications created with the ASP.NET Rendering SDK"
slug: "troubleshooting-applications-created-with-the-asp-net-rendering-sdk"
abstract: "Investigate and resolve issues in your ASP.NET rendering hosts."
---
# Troubleshooting applications created with the ASP.NET Rendering SDK

> [!important]
> If you integrated your app before , it's using the legacy ASP.NET Core Rendering SDK, version 22 or earlier. This SDK is no longer receiving updates, so we recommend that you [upgrade to the latest version of the new](https://doc.sitecore.com/xmc/en/developers/asp-net/latest/asp-net-core-sdk/upgrade-from-v22.html) .

This topic describes issues you might encounter in applications created with the ASP.NET Rendering SDK and explains possible solutions.

<details>
<summary><h2>Handling validation errors for request headers</h2></summary>

If you are getting errors about request header validation and are using the Layout Service REST API, you can define a list of headers to be skipped during header validation.

To configure headers that skip the validation process:

- In the `Startup.cs` file, provide an array of headers to the `AddHttpHandler` extension method as the `nonValidatedHeaders` parameter. For example:

    ```csharp
    services
         // ...
        .AddHttpHandler("your_handler_name".Name, sp =>
        {
            var factory = sp.GetRequiredService<System.Net.Http.IHttpClientFactory>();
            var client = factory.CreateClient("your_handler_name");

            client.BaseAddress = "your_handler_uri";

            return client;

         }, new [] { "User-Agent" })
        // ...
    ```

Alternatively, define the list of headers in the `appsettings.json` file and provide them as a configuration property:

1. In the `appsettings.json` file, specify a new property with an array of strings as a value. For example:

    ```JSON
    "Sitecore": {
      "HeadersToSkipValidation": ["User-Agent"]
    }
    ```

2. In the `\Configuration\SitecoreOptions.cs` file, specify the new property:

    ```csharp
    public class SitecoreOptions{
     // ...
     public string[] HeadersToSkipValidation { get; set; } = new string[0];
     // ...
    }
    ```

3. Finally, in the `Startup.cs` file, use the `AddHttpHandler` extension method and provide the array of headers as the `nonValidatedHeaders` parameter:

    ```csharp
    services
    // ... other code
       .AddHttpHandler("<your_handler_name>", sp =>
       {
           var factory = sp.GetRequiredService<System.Net.Http.IHttpClientFactory>();
           var client = factory.CreateClient("default");
           client.BaseAddress = Configuration.LayoutServiceUri;
           return client;
      }, Configuration.HeadersToSkipValidation) 
    // ... other code
    ```

</details>