What is 503 Service Unavailable Error

A 503 Service Unavailable Error is an HTTP response status code indicating that a webserver is temporarily unable to handle the request. This article describes what a 503 Service Unavailable Error means, and some troubleshooting tips.

What is an HTTP 503 Error#

One of the most common errors that occur when browsing the web is the “503 Service Unavailable Error”. Once you visit a any website page, your browser sends a request to the hosting server of the site and which response the requested data along with response code. The response status code returned by the server and tells the client whether the request has been successful or not. The Response codes are categorized into different codes in the 500 to 599 range, which are indicating a server error.

Mostly, the HTTP status code 503 is a generic error response returned when the server cannot handle the request. There are dozens of possible reasons for a server is not ready to complete the request and return a 503 error. This may be due to the server being overloaded or down for maintenance.

You can’t do more if your visiting site throwing 503 Error. Even though you can try following options:

• Try to clear cache of your browser and load again.
• Re-open your browser and try to open page again. If the page that shows a 503 error is cached, the browser will request a new version of the page after the cache is cleared.
• If the error is server-side the webmaster may fix the webserver issue in the meantime.
• You can contact with the website owners.

Troubleshooting 500 Error#

There are dozens of reasons that could cause the 503 Internal Server Error. Following are the most common reasons:

Your server in backend may go through regular service or software maintenance. For example, if you have a WordPress site, it is automatically updated to the latest version whenever there’s a new release. During this update process, WordPress returns a 503 Service Unavailable error.

• Commonly, a misconfigured firewall can cause a 503 error. This usually happens when the application is using a content delivery network (CDN). The server firewall may recognize the requests from the CDN as an attack and block them, resulting in a 503 error.
• A malicious code that is injected into your website may result in a 503 error.
• Distributed Denial of service (DDoS) attack. A DDoS attack is an attempt by a malicious party to flood the bandwidth or resources of your system and overload it. When the system gets overloaded, it is not able to serve the requests.
• Issues with plugins and themes. If you are running WordPress or similar CMS, the 503 error can appear after updating or modifying a plugin/theme.
• Node.js server. If you have Node.js based site, check if the Node.js server crashed or just not running.

It’s a best way to determine the error by checking server log file. You can find log file on different location depends on your Linux distribution and web server. Below are the most common log location:

/var/log/apache2/error.log
/var/log/httpd/error_log
/var/log/nginx/error_log

If your application is built on Node.js, check the Node.js logs.

Conclusion#

A 503 Service Unavailable Error is an HTTP response status code indicating that a server is temporarily unable to handle the request.

If you have any questions or feedback, feel free to leave a comment.