Скачать или смотреть How to Fix the System.ArgumentNullException in ASP.NET Core 6.0

Encountering a `500 Internal Server Error` in your ASP.NET Core 6.0 Web API project? Learn how to resolve the `System.ArgumentNullException` and ensure your application runs smoothly in both development and production environments.
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This video is based on the question https://stackoverflow.com/q/70150656/ asked by the user 'hanushic' ( https://stackoverflow.com/u/17173106/ ) and on the answer https://stackoverflow.com/a/70151171/ provided by the user 'foad abdollahi' ( https://stackoverflow.com/u/11222433/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the System.ArgumentNullException in ASP.NET Core 6.0

When developing an ASP.NET Core 6.0 web API application, many developers encounter a variety of challenges. One such issue is the frustrating System.ArgumentNullException, specifically with the parameter uriString. This error typically surfaces when transitioning your project from the development environment to production. In this guide, we'll explore the root cause of this issue and guide you through a clear step-by-step solution to resolve it.

Problem Overview

The System.ArgumentNullException often appears when the application fails to create a URI from a null string. In your case, the problem arises during the construction of an HttpClient within your web API when deployed in a production environment.

Here are the symptoms you reported:

When running your project with dotnet run in development mode, you received a 200 OK response for a GET request.

However, when you built the project with dotnet publish -c Release, the same GET request returned a 500 Internal Server Error.

The error logs pinpointed the source of the issue to a missing URL configuration. Let’s dive into the solution.

Diagnosing the Issue

Understanding the Error Message:

The error states:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that the application is attempting to create a Uri object but does not receive a valid string as input.

Identifying the Code Segments:

Relevant code snippets include the parts where you configure your HttpClient:

[[See Video to Reveal this Text or Code Snippet]]

Solution: Ensure Proper Configuration

Here are the steps to ensure that your application’s settings are correctly configured for both the development and production environments.

1. Modify Your appsettings.json

It appears that your application configuration did not include the necessary URL for accessing the payment service in your production settings. Update your appsettings.json file to include the relevant configuration as follows:

[[See Video to Reveal this Text or Code Snippet]]

2. Verify Environment-specific Configurations

Ensure that you have the correct environment settings for production, particularly those related to sensitive information such as payment URLs. If you don't have different configurations for your development and production settings, consider implementing them effectively.

3. Check Environment Variables

If you're deploying using a container or a cloud provider, double-check your environment variables for production. Make sure that they are set correctly to pick up the required configuration values.

4. Test Your Configuration

After making these adjustments, rebuild your application using:

[[See Video to Reveal this Text or Code Snippet]]

Then, retry accessing your endpoint to confirm that the 500 Internal Server Error is resolved.

Conclusion

Managing configurations and understanding how your application behaves in various environments is crucial to successful deployment. The System.ArgumentNullException often signifies misconfigured settings, especially regarding important URIs for services. By ensuring your appsettings.json and any environment variables are correctly set, you can avoid these frustrating issues and improve the stability of your application.

Now, you are equipped with the necessary steps to identify and fix this error. Happy coding!