The 504 Gateway Timeout Error indicates that the server didn’t receive a timely response from an upstream server it needed to access in order to complete a request. This can happen because the other server is not functioning properly, overloaded, or down.

 

To simplify it further, this error occurs when two servers are involved in processing a request. The first server (typically the main server) times out, waiting for a response from the second server (upstream server).

Error Code	504 Gateway Timeout Error
Error Type	Server-side
Error Variations	504 Gateway Timeout504 Gateway Timeout NGINX NGINX 504 Gateway Timeout Gateway Timeout Error Error 504 HTTP Error 504 HTTP Error 504 — Gateway Timeout HTTP 504 504 Error Gateway Timeout (504)
Error Causes	Server connectivity issues Network connectivity problems DNS issues Firewall issues

This is how the process works: every time you visit a website in your browser, the browser sends a request to the web server where the site is hosted. The server processes the request and responds with the requested resources.

The server response includes one of many HTTP status codes to indicate the response’s status to the browser. But not all these HTTP status codes are errors. For instance, a 200 OK status code means that the server processed the request successfully and “Everything is OK.”

The 5xx class of HTTP status codes indicates that something’s wrong with the server, the server is aware of it, and it cannot carry out the client request. As a result, they’re also referred to as Server Error 5xx status codes.

Officially, five status codes are specified under the 5xx class (500, 501, 502, 503, 504). You may come upon many unofficial codes too (506, 507, 509, 520, etc.).

The 504 Gateway Timeout error manifests itself in various forms. Here are some ways it usually shows up:

The 504 Gateway Timeout error is similar to the 502 Bad Gateway error, which indicates that the first server received an invalid response from the second server (upstream server).

Variations of the 504 Gateway Timeout Error

The browser displays any 504 Gateway Timeout error inside it, just like any other error. As there are various operating systems, web servers, browsers, and user agents, it can show up in multiple ways.

Below are a few common 504 error message variations that you may run into:

• 504 Gateway Timeout
• 504 Gateway Timeout NGINX
• NGINX 504 Gateway Timeout
• Gateway Timeout Error
• Error 504
• HTTP Error 504
• HTTP Error 504 — Gateway Timeout
• HTTP 504
• 504 Error
• Gateway Timeout (504)
• This page isn’t working — Domain took too long to respond
• 504 Gateway Time-out — The server didn’t respond in time
• The page request was canceled because it took too long to complete
• Site visitors: There was an issue serving your request, please try again in a few minutes.
• Site Owners: There was a gateway timeout. You should visit your error log for more information.
• A blank white screen

All the above error responses, though worded differently, point to the same 504 Gateway Timeout server error.

Web servers and websites can customize how they show the 504 Gateway Timeout error to users. Some of them can be cool! It’s an excellent tactic to quell their visitors’ disappointment.

 

What Are the Causes of the 504 Gateway Timeout Error?

As the 504 error is due to a timeout between servers, the problem probably isn’t with the client’s device or internet connection. That also includes your device and connection.

A 504 Gateway Timeout error indicates that the web server is waiting too long to respond from another server and “timing out.” There can be many reasons for this timeout: the other server is not functioning properly, overloaded, or down.

The other server need not always be external (e.g. CDN, API gateway). It can also be a server-like entity within the main web server (e.g. reverse proxy server, database server).

SEO Impact of the 504 Gateway Timeout Error

All 5xx errors prevent a webpage from loading, making them detrimental to user experience. Hence, search engines like Google take these errors seriously. If the error persists for a long duration, it may even lead to deindexing the webpage from the search engine results.

For example, when Google spiders stumble upon a 503 Service Unavailable error, they’ll understand that it’s a temporary issue as it’s mostly used to enable site maintenance mode. Thus, they’ll try to crawl the page again later.

A 504 Gateway Timeout error isn’t necessarily temporary as it can be due to multiple reasons. If your site is down for just a few minutes, and if the spiders are trying to crawl it multiple times every minute, they’ll try to serve the page from their cache.  They wouldn’t even notice it.

But if your site is down for 6+ hours or more, then Google will consider the 504 error as a serious site-wide issue that you need to fix as soon as possible. This can impact your SEO negatively.

Google Search Console is one of the best SEO tools to monitor your website’s HTTP 5xx errors.

While Google Search Console is one of the best SEO tools for monitoring your website’s HTTP 5xx errors, it might not catch every error. For a more thorough examination, the Website Crawler by Sitechecker emerges as a vital resource.

This tool is designed to detect all errors on your site, including HTTP 5xx errors, ensuring you have a comprehensive overview of what needs fixing to maintain your SEO standing.

How to Fix the 504 Gateway Timeout Error?

Without knowing exact details about the site, such as its server configuration, hosting plan, third-party plugins, and the traffic it attracts, you may find it frustrating and overwhelming to fix a 504 Gateway Timeout error.

Since many variables are involved, I recommend you to start by fixing client-side issues, which are pretty rare, and then move towards fixing server-side problems. They’re usually the culprits with 504 errors.

 

1. Try Reloading the Webpage

One of the first things you can try when encountering a 504 Gateway Timeout error is to wait a few minutes and try reloading the page.

You can press the F5 keyboard shortcut to refresh/reload the webpage in most browsers. To remove the page’s browser cache before reloading, you can press the CTRL+F5 shortcut combo instead.

While you’re at it, you can also try loading the site in a different browser to rule that out as an issue. As most 504 errors are due to temporarily overloaded servers, using this solution should make your site come right back.

If waiting and reloading the site doesn’t fix the 504 error issue, you can check whether a site is down for everyone or just you. Two useful online tools to test a site for downtime are Down for Everyone or Just Me and Is It Down Right Now?

2. Reboot Your Network Devices

Sometimes, problems with your network devices like modem or router could lead to a 504 Gateway Timeout error. Rebooting these devices could help you with fixing the problem.

While you can switch off all these networking devices in any order, the order you switch them back on is important. Typically, turn these devices on from the “outside-in,” following the connection order from the internet service provider to your main client device.

3. Check Your Proxy Settings

A proxy server sits between your device and the internet. It’s mostly used to enhance online privacy by hiding private information (e.g. device location) from websites and webservers (e.g. using a VPN).

While it’s rare for proxy servers to cause a 504 error, incorrect proxy server settings can sometimes be the reason. You can disable the proxy server and try reloading the webpage to see whether it’ll fix the error.

Most clients don’t use a proxy service, so you can skip this step if you’re confident that you don’t use any proxy server. However, you might have set it without you even knowing about it. I’d suggest you check your device’s and browser’s proxy settings to rule this cause out.

4. Check for DNS Issues

A 504 Gateway Timeout error can also be caused by DNS issues on the server-side or the client-side (or both).

The most probable reason for a server-side DNS issue is the FQDN (fully qualified domain name) not resolving the correct IP address or the DNS server not responding. Usually, this occurs when you’ve just migrated your site to a new server or host. Hence, it’s important to wait for the domain’s DNS records to propagate fully, which can take up to 24 hours.

You can use free tools like whatsmydns.net DNS Checker or DNSMap to see if your DNS has propagated around the globe.

For fixing client-side DNS issues, you could try flushing your local DNS cache. It’s like clearing your browser cache, except here, you’re flushing the DNS cache from the operating system.

If you’re using Windows, you can flush the DNS cache by opening the Command Prompt and entering the following directive:

ipconfig /flushdns

You should see a “Successfully flushed the DNS resolver Cache.” message if it worked.

For the latest macOS versions, you can open the Terminal and run the following command:

sudo killall -HUP mDNSResponder

You won’t see any notification in macOS when the process finishes, but you can change that by appending the command with your custom message.

sudo killall -HUP mDNSResponder; DNS Cache was cleared successfully

If you’re using older macOS versions, the command you need to enter varies based on which version of macOS you’re running. For more details, you can refer to the macOS section in Kinsta’s in-depth flush DNS tutorial.

If you’re using the Linux operating system, then the process is quite similar to macOS as even Linux uses the Terminal as its command-line interface. Since there are many Linux distributions, the exact command you need to run may vary from one distro to another.

Finally, you can change your client-side DNS servers temporarily. By default, your ISP assigns the DNS servers automatically to you. But you can change these to public DNS IPs temporarily.

Some reliable DNS servers you can try out are Google Public DNS, Cloudflare 1.1.1.1, Quad9 DNS, and Cisco OpenDNS.

5. Disable Your Site’s CDN Temporarily

Sometimes, the issue could also be with your content delivery network (CDN). If a site’s origin server isn’t reachable, most CDNs will try to serve the full webpage from their cache.

But most CDNs don’t enable this feature by default as it’s complex to cache dynamic assets on most sites (e.g. the WordPress admin dashboard).

A straightforward way to troubleshoot this is to disable your CDN temporarily. For example, if you’re using the free CDN Enabler WordPress plugin to link your site assets to the CDN URLs, then you can deactivate the plugin and test reloading your site.

The same goes for using any other plugin you may use to connect to your CDN (e.g. WP Rocket, Breeze, W3 Total Cache).

If you can’t access your site’s admin dashboard, you can disable the plugin via SFTP by renaming the plugin’s folder name.

CDNs like Cloudflare or Sucuri, which provide full proxy services, have extra firewalls between their edge servers and your origin server. Hence, you may encounter HTTP 5xx errors more frequently while using them. Most of them cache 5xx errors returned by your origin server, so it’s easy to troubleshoot them.

Cloudflare’s free plan is prone to throw up a 5xx error. Unfortunately, since it’s a full proxy service, there’s no quick way to disable it. But before you blame Cloudflare for it, know that Cloudflare shows two variations of the 504 Gateway Timeout error.

504 Gateway Timeout at Cloudflare (Variation 1)

Cloudflare will show you a custom 504 Gateway Timeout error screen when your site’s origin server responds with a standard HTTP 504 response.

Here, the issue lies with your web server and not Cloudflare. You can try fixing it with the other solutions mentioned below or contact your hosting provider’s support for technical help.

504 Gateway Timeout at Cloudflare (Variation 2)

If Cloudflare causes the 504 Gateway Timeout error, the error screen will mention “cloudflare,” which is currently the standard server name for all Cloudflare assets. Usually, the error screen will appear as below:

Since Cloudflare itself is unresponsive, you’ll not see any Cloudflare-branded error screen here.

Most likely, Cloudflare is already aware of the issue and is working on a fix already. You can confirm this by checking the Cloudflare System Status webpage. Alternatively, you can get in touch with Cloudflare support for a quicker resolution.

504 Gateway Timeout at Cloudflare Due to Large Uploads

The size of your uploads to your site can also be a reason for the server timeouts. Cloudflare limits upload file size (per HTTP POST request) to just 100 MB on both Free and Pro plans.

The issue can be on your host’s end or with Cloudflare. You can find out the exact cause by bypassing Cloudflare with your DNS hosts file and trying your upload again.

If you’re using Cloudflare with WordPress, we recommend using their free plugin and excluding critical URLs from caching (such as the WordPress admin dashboard).

6. Check Server Issues With Your Host

Server issues are one of the most common reasons for facing a 504 Gateway Timeout error. Since most WordPress sites are hosted on Nginx or Apache webservers, Nginx or Apache is waiting for a response from something and timing out.

Many clients come to Kinsta for exactly this problem they’re facing at other hosts. The conversation goes something like this:

"We’re getting around 100k visitors per month with more than 200k views. Currently, we’re hosting with ____ and we experience 504 errors constantly due to server overload. I don’t like how ____ handled the problem, and we were also advised that we will have to move to their dedicated plans soon, which I believe is not necessary."

High-traffic and ecommerce sites are more prone to getting 504 errors because of server overload as they generate many uncacheable requests. However, this issue can crop with any site, including simple blogs. Many hosts will ask you to upgrade to a high-tier plan to fix the issue, which in most cases is unnecessary.

We use LXD managed hosts and orchestrated LXC software containers for each site. Thus, every site is housed in its own isolated container with access to all the software required to run it (Linux, Nginx, PHP, MySQL). The resources are 100% private and aren’t shared with any other site, even your sites.

Most hosts providing shared hosting plans don’t have this capability. Hence, a high-traffic site hosted on the same server as yours may cause your site to throw up a 504 error too.

Apart from isolating each site in its container, Kinsta has also designed its infrastructure to handle thousands of concurrent connections easily. Kinsta even hosts the MySQL databases at localhost, not a remote server. This means no latency between machines, resulting in faster queries and fewer chances of timeouts occurring.

An overloaded server isn’t the only cause for a server timeout. There can be many other reasons for the 504 error:

Slow Server Infrastructure

The server you use to host your site may not have enough resources to handle the load. It’s like playing a modern, graphics-intensive videogame on a decade-old PC.

The server just hangs up trying to serve the website. The only solution to this problem is to upgrade to a server with better infrastructure. For this reason, even Kinsta’s most basic hosting plan will handle a static site with medium traffic.

Needs More PHP Workers

PHP workers are used to execute your site’s code. An ecommerce site that gets 50,000 visitors per month needs a lot more resources than a simple blog with the same amount of traffic. If all the server’s PHP workers are busy, they’ll build up a queue.

When the queue gets too big, the server disregards old requests, which may cause the server to throw up a 504 gateway error. You can ask your host about increasing your number of PHP workers. This’ll allow your site to execute multiple requests simultaneously.

Firewall Issues

Your server’s firewall could have some errors or an improper configuration. Perhaps, a few of its rules prevent the server from establishing a connection properly. To know if your firewall is the culprit, you can check your server’s error logs.

Network Connectivity Problems

Connectivity issues between the proxy server and the web server could cause delays in responding to HTTP requests. If you use a load balancer, there could also be network connectivity issues with it.

HTTP Timeouts

HTTP timeouts can occur when a connection between the web server and the client is kept open for too long. With WordPress sites, this usually happens when running WordPress imports. One way to resolve this issue is to switch to a faster internet connection.

You can also use a tool with support for WP-CLI to run the scripts directly on the server, bypassing the HTTP connection entirely. For instance, you can use the wp import WP-CLI command to run the WordPress Importer plugin directly through the command-line interface.

Important: 504 Gateway Timeout errors look similar to 503 Service Unavailable errors or 502 Bad Gateway errors. But they’re all different. If you’re experiencing a 504 error, open a support ticket to get your issue fixed.

For monitoring your site’s downtime on your own, you can use a tool like updown.io. It’ll check your website’s status (or any URL) periodically by sending an HTTP request to it. You can set the check frequency from 15 seconds to 1 hour. If your website isn’t responding correctly, it’ll notify you with an email or an SMS.

You’ll get a generous quantity of free credits with every account of updown.io, but if you’re looking for cheaper alternatives, you can check out WebGazer or UptimeRobot. Both these tools will help you monitor your site’s uptime every 5 minutes for free. That’s decent enough for most website owners.

Monitoring your website will give you an idea of how often it’s down. This is especially helpful if you’re using a shared hosting provider. Most application, database, and managed WordPress hosts take care of this automatically for you. Hence it’s always recommended to go with them.

7. Check for Spam, Bots, or DDoS Attacks

Malicious attackers can bring your web server to a crawl by sending too many and/or resource-intensive requests. If your site is getting spammed by bots or undergoing a DDoS attack, it can overwhelm your server and result in 504 Gateway Timeout errors for many genuine users.

You can look at your server traffic and analytics to see if you can spot any irregular patterns in the site traffic.

Start your investigation by looking at the top client IPs. It’ll give you an idea of who generates the maximum number of requests, and from where. If your server suddenly uses up enormous bandwidth or attracts a lot of traffic, then this report will come in super handy.

Next, you can check out the Cache Analysis report. Here, you can see how many requests are bypassing or missing the cache, or being served from the cache. For performance and stability reasons, you want to cache as many requests as possible, but it’s not always possible to achieve that.

For example, WooCommerce sites generate many uncacheable requests for features such as the shopping cart and the checkout process.

Finally, you can use a security plugin to beef up your website’s security by spotting and blocking worrisome traffic/IPs. You can ask your host to block certain IPs too.

Depending upon the length and scale of the attack, this could be a never-ending process of blacklisting IPs as many attackers change their IPs and proxy addresses after getting blocked.

8. Repair Your Corrupted WordPress Database

Sometimes, a 504 Gateway Timeout error can be because of a corrupt database, especially in WordPress sites. Typically, this is due to corrupted database tables or files. Sometimes, it can also be caused by a serious security issue like your site or database being hacked.

Repairing a corrupted WordPress database depends on the problem. Plugins like WP-DBManager make it easy to diagnose database issues and repair them. 

9. Check Your Site’s Plugins and Themes

In most cases, third-party plugins and themes don’t cause 504 errors. But there’s a slight chance that they might cause server timeouts, usually by queuing up many uncached requests generated by the plugin/theme. As this ties up a lot of your server’s PHP workers, it can cause 504 errors.

A great example of this issue is WooCommerce, a plugin installed to add ecommerce functionality to WordPress sites.

The simplest way you can troubleshoot this problem is by deactivating all your plugins. Remember, you won’t lose any data if you just deactivate a plugin.

If you can access your admin dashboard, you can go to the Plugins screen, select Deactivate from the bulk actions menu, checkmark all the plugins, and then hit the Apply button. This will disable all of your plugins.

If you can’t access your admin area, you can disable plugins via SFTP using the method described before. Just rename the main plugin folder name to disable all the plugins in bulk.

Once you’ve deactivated all the plugins, check whether your site loads properly. If it works, you must activate each plugin, testing the site after enabling every plugin.

Finally, make sure that your plugins, themes, and WordPress core are up to date. Also, ensure that your server is running the recommended version of PHP.

If you feel this to be too overwhelming, you can always reach out to your host for help. 

In the worst-case scenarios, like an inefficient query or bad code in a plugin/theme, you can bring in a WordPress developer to fix the issue.

10. Check Error Logs

Viewing error logs can be very helpful when troubleshooting and debugging 504 errors on your site. This can help you narrow down an issue on your site quickly, especially if it’s resulting from a demanding plugin on your site.

If your host doesn’t have a logging tool, then you can enable WordPress debug mode by adding the following code to your wp-config.php file:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

The WP_DEBUG constant enables or disables the WordPress debug mode. It has two optional companion constants that can extend its features. The WP_DEBUG_LOG constant directs all errors to be saved to a debug.log file within the /wp-content/ directory. If you don’t see this file, you can always create one.

The WP_DEBUG_DISPLAY constant controls whether debug logs show up on the HTML page. Setting this to false will hide all errors, but you can review the errors later, as you’ve also defined WP_DEBUG_LOG as true.

Important: If you have WP_DEBUG enabled in the Kinsta environment, it’ll route all errors to the debug.log file and not the error.log in the MyKinsta dashboard.

You can also download the raw WordPress error log files via SFTP. Typically, you can find error logs in your server’s root directory in a folder named “logs.”

Lastly, you can check the server log files. Depending on which server you’re using to host your WordPress site, they’re commonly found in these locations:

• Apache: /var/log/apache2/error.log/
• Nginx: Hai trovato utile questa risposta?
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