304 Not Modified Explained

304 Not Modified Explained

Learn more about what causes the "304 not modified" status code, how to fix it, and some of the more common reasons for a 304 you should be aware of!

You may have seen a 304 Not Modified status code before, but what does it mean? 


Is it something wrong with the server or the client? 


The 304 Not Modified status code can be a confusing one. 


It's not as straightforward as other HTTP codes, but it can still be fixed with a bit of knowledge and the right tools. 


In this post, we will explore what causes this status code and how to fix it. You'll also learn about some of the more common reasons for 304s that you should be aware of!


Let's dive in!


What Are HTTP Status Codes?


Before we dive deep into the 304 Not Modified status code, let's first try to understand what HTTP status codes mean.


In a nutshell, the Internet has two major players: servers and clients. Let's say that you're using your browser, Google Chrome, to access a web page. You're actually accessing the Internet through a web client.


The server is the thing on the other side of the communication that receives your request to access a page. 


An HTTP status code is exchanged between the server and the browser every time you make a request to your server to access a resource. 


There are a few different classes of HTTP response status codes. They all inform a user whether a specific HTTP request has been successfully completed. The five core status codes include:


  • 1xx status codes: Informational requests
  • 2xx status codes: Successful requests
  • 3xx status codes: Redirects
  • 4xx status codes: Client errors
  • 5xx status codes: Server errors  


For example, the 4xx status codes – such as the 403 Forbidden and 406 Not Acceptable – are client errors. They indicate that something that is happening on the client-side is the issue. Status codes in the 5xx group indicate the opposite: that the problem is something with the server.


On the other hand, status codes in the 3xx group – such as the 304 Not Modified – indicate a redirection. In addition, some status codes – like the 301 Moved Permanently307 Temporary Redirect, and 308 permanent redirects – affect your user experience and SEO performance. 


As some of these status codes can negatively affect your SEO and user experience, fixing them is critical.


What Does 304 Not Modified Mean?


HTTP 304 is a status code that tells your browser that: "The requested resource has not been modified since the last time you accessed it." It indicates that the client, which made the request conditional, already has a valid representation. 


In short, the server tells your or your visitor's browser that the resources cached in the browser haven't been updated since the last time you or the visitor visited that page. 


Consequently, the browser will retrieve a saved version of that page from the cache to help improve page speed and delivery.


What Causes a 304 Not Modified Status Code?


A 304 Not Modified is usually due to something on the client-side of things. In most cases, it's the user who has to develop a solution to the problem.


The three most common causes of a 304 Not Modified are:


  • The user has a virus or malware on their computer that has corrupted their browser.
  • The user has installed or uninstalled the software on their computer, which corrupted the registry. A corrupted registry impacts the browser, as well.
  • The user has corrupted files in their internet browser. Corrupted files prevent the internet browser from saving web pages and updating information.

How Do I Fix 304 Not Modified?

Although there are not much website owners can do, users can try a couple of things to troubleshoot the problem.


Here are three possible fixes to the 304 Not Modified status code:

Clear Browsing Data

Clearing the browsing data is the best way to ensure your cache is cleared so it can try to access the URL you're requesting.


Clearing your cache will make sure that you're not looking at an old version of a web page. This can be done by going to Settings > Clear Cache and Data, but this varies depending on what device or browser is being used.

Get Rid of Viruses or Malware

A 304 not modified code could be happening because your browser is corrupted with a virus or malware. Try to get rid of a potential virus or malware by using an antivirus.

Uninstall New Extensions

Extensions can take complete control over a system at any point in time, whether that means changing your PHP code, CSS, HTML, or database. So make sure to uninstall any new additions you may have made recently before doing anything else.


The 304 Not Modified status code indicates that the website the user is requesting hasn't been updated since the last time they accessed it.


The best way to fix the 304 Not Modified status code is to:


  • Clear your browsing data
  • Get rid of viruses or malware
  • Uninstall new extensions


If none of these solutions work, the problem may be technical. In this case, the user should consider asking a web developer for help. 


If you want to learn more about all the different types of status codes, we've put together this comprehensive HTTP status code cheat sheet that contains all the ABCs of HTTP status codes. 

And after you're done with all your hard work studying up on these codes, make sure to invest in proper 
website maintenance services. Regular monitoring and upkeep will ensure that you offer an exceptional customer experience at all times!