Getting 304 (Not Modified) After New Deploy In Firebase App Hosting

Mar 10, 2025 by ADMIN 68 views

**Getting 304 (Not Modified) after new deploy in Firebase App Hosting**

Introduction

As a developer, deploying a new version of your web application is an essential step in the development process. However, when using Firebase App Hosting, you might encounter a peculiar issue where your browser returns a 304 (Not Modified) status code after a new deployment. This can be frustrating, especially when you're eager to test the latest changes to your application. In this article, we'll delve into the world of caching policies, browser cache, and Firebase App Hosting to understand what's happening and how to resolve this issue.

Understanding Caching Policies

Before we dive into the specifics of Firebase App Hosting, let's take a step back and understand how caching policies work. Caching policies determine how a web server responds to requests from a client, such as a web browser. There are two primary types of caching policies:

Cache-Control: This policy is used to control caching behavior on the client-side (i.e., the web browser). It specifies how long a resource should be cached and whether it can be reused.
ETag: This policy is used to control caching behavior on the server-side. It provides a unique identifier for a resource, which the client can use to determine whether the resource has changed.

Browser Cache

When you visit a website, your web browser caches the resources it loads, such as HTML, CSS, and JavaScript files. This caching is done to improve page load times and reduce the number of requests made to the server. However, when you deploy a new version of your application, the browser may still serve the cached version of the resources, rather than the updated version.

Firebase App Hosting Caching Policy

Firebase App Hosting uses a caching policy that is based on the Cache-Control header. When you deploy a new version of your application, Firebase App Hosting sets the Cache-Control header to public, max-age=3600. This means that the resources are cached for 1 hour (3600 seconds) and can be reused by the client.

However, when you deploy a new version of your application, Firebase App Hosting also sets the ETag header to a unique identifier for the new version. This ETag is used to determine whether the resource has changed.

The 304 (Not Modified) Issue

So, what happens when you deploy a new version of your application and hit refresh in the browser? The browser sends a request to the server with the ETag of the cached resource. Firebase App Hosting checks the ETag and determines that the resource has not changed. As a result, it returns a 304 (Not Modified) status code, indicating that the browser should serve the cached version of the resource.

Resolving the Issue

To resolve the 304 (Not Modified) issue, you can try the following:

Clear the browser cache: Try clearing the browser cache to ensure that the browser is serving the latest version of the resources.
Use a cache-busting technique: Use a cache-busting technique, such as appending a query parameter to the URL of the resource, to force the browser to reload the resource.
Disable caching: Disable caching on the client-side by setting the Cache-Control header to no-cache or no-store.
Use a different caching policy: Use a different caching policy, such as the ETag policy, to determine whether the resource has changed.

Conclusion

In conclusion, the 304 (Not Modified) issue in Firebase App Hosting is a caching policy issue. By understanding how caching policies work and how Firebase App Hosting uses caching, you can resolve this issue and ensure that your application is serving the latest version of the resources.

Additional Tips

Here are some additional tips to help you resolve the 304 (Not Modified) issue:

Use a versioning strategy: Use a versioning strategy, such as appending a version number to the URL of the resource, to ensure that the browser is serving the latest version of the resources.
Use a content delivery network (CDN): Use a CDN to serve your resources, which can help to reduce the impact of caching issues.
Monitor your application's performance: Monitor your application's performance to identify any caching issues and resolve them promptly.

Frequently Asked Questions

Here are some frequently asked questions about the 304 (Not Modified) issue in Firebase App Hosting:

Q: Why do I get a 304 (Not Modified) status code after deploying a new version of my application? A: You get a 304 (Not Modified) status code because the browser is serving the cached version of the resources, rather than the updated version.
Q: How can I resolve the 304 (Not Modified) issue? A: You can resolve the 304 (Not Modified) issue by clearing the browser cache, using a cache-busting technique, disabling caching, or using a different caching policy.
Q: What is the caching policy used by Firebase App Hosting? A: The caching policy used by Firebase App Hosting is based on the Cache-Control header, which sets the resources to be cached for 1 hour (3600 seconds) and can be reused by the client.