Troubleshooting Cookies Not Being Sent in Express and React Applications

Discover effective solutions for solving cookie-related issues in your Express and React applications, specifically when dealing with `cross-domain` scenarios.
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This video is based on the question https://stackoverflow.com/q/68725629/ asked by the user 'Juan' ( https://stackoverflow.com/u/16631936/ ) and on the answer https://stackoverflow.com/a/68906201/ provided by the user 'Juan' ( https://stackoverflow.com/u/16631936/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting Cookies Not Being Sent in Express and React Applications

In a modern web application, managing user sessions securely is crucial. However, developers often encounter challenges when it comes to cookies, especially in scenarios involving different domains. If you are using Express for your backend and React for your frontend—and are experiencing issues where cookies are not being sent, despite configuring your fetch requests to include credentials—this guide will help unravel the problem and provide a solution.

Understanding the Problem

You are deploying a web application where the frontend and backend are hosted on different domains. You have set credentials in your fetch request to 'include', but you notice that cookies are not being sent, which results in the server not recognizing the user session. This can be frustrating, especially when it appears that everything is set up correctly.

Common Signs of the Issue:

Cookies are not being set on the client-side.

The server logs output User: undefined for the authenticated user.

You might be seeing CORS-related warnings or errors in the console, even if you believe they are configured correctly.

Exploring the Solution

After diagnosing the issue, it became clear that the problem lay within the configuration of cookie management in the backend. Below are the steps taken to resolve the issue.

1. Identify the Configuration Flaw

Initially, the cookies were being managed using cookie-session, which had the configuration for sameSite set to 'lax'. While this might work for most scenarios, it led to the cookies not being sent in a cross-domain context. When switching to sameSite: 'none', you encountered another error related to the secure flag needing to be true in production environments.

2. Adopt the express-session Package

To overcome this issue, switching to the express-session package, a more robust solution for handling sessions, is recommended. Below is an example of how to properly configure it:

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

Key Configuration Options Explained:

trust proxy: This option enables Express to recognize reverse proxies and correctly set the secure flag on cookies.

secure: true: Ensures that cookies are only sent over HTTPS connections. This is mandatory when using sameSite: 'none' to comply with browser security policies.

sameSite: 'none': This allows cookies to be sent in cross-site contexts, which is essential for cross-domain applications.

3. Update Your Fetch Request:

Also, ensure your fetch request maintains its configuration for sending credentials:

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

Conclusion

Setting up cookie management can be tricky, especially in cross-domain scenarios. By making the adjustments detailed above, notably switching to express-session and ensuring the correct cookie settings, you can overcome challenges associated with sending cookies in your Express and React applications.

If you've found this post helpful or have any questions, feel free to reach out or leave a comment! Happy coding!

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