Sometimes you may get 503 Service Temporarily Unavailable error in NGINX due to various reasons. In this article we will look at what is 503 service temporarily unavailable error, and how to fix 503 service temporarily unavailable error in NGINX.
What does 503 Service Temporarily Unavailable Error in NGINX
503 Service Temporarily Unavailable Error means that NGINX is unable to handle the request as it is temporarily overloaded or facing resource constraints. It is different from 500 internal server error where the server is simply unable to process your request. In this case, the server continues to function properly but has chosen to return 503 error code.
Bonus Read : How to Fix 500 Internal Server Error in NGINX
How to Fix 503 Service Temporarily Unavailable Error in NGINX
Here is how to fix 503 service temporarily unavailable error in NGINX.
1. Reboot NGINX Server
One of the easiest ways to fix 503 service temporarily unavailable error is to simply restart NGINX server. Many times, NGINX may get overloaded due to too many open connections and temporary files. Restarting your server will close all these open connections and delete temporary files that are causing the bottleneck. If NGINX is a reverse proxy with multiple web servers, make sure to reboot even the web servers down the chain to ensure that your website/application is completely refreshed.
Bonus Read : How to Fix 504 Gatweway Timeout Error in NGINX
2. Check for Unexpected Updates / Maintenance
Have you enabled auto-updates in your web site/application? If so, then it might be downloading/installing updates for one or more plugins. This is quite common in CMS based systems like WordPress and Magento. In such cases, just turn off auto-updates in your system.
Similarly, check if you have any scheduled maintenance running in the background. In such cases also, your web server will return 503 service temporarily unavailable.
Bonus Read : How to Fix 502 Bad Gateway in NGINX
3. Server Connectivity
NGINX may also throw 503 service temporarily unavailable error if it is unable to connect to the web server (e.g Apache) or any of the third-party APIs.
Since today’s web architecture requires multiple web servers and third-party services, NGINX is likely to give 503 service temporarily unavailable if any of them goes down. In such cases check if all web servers and third party services are up and running.
Bonus Read : How to Increase Request Timeout in NGINX
4. Examine Server Logs
NGINX server log records the IP address, device, requested URL, response code and date time for each request. You can use any server log monitoring tool to find out which requested URL gives 503 service temporarily unavailable error. Once you have identified the problematic URLs, you can investigate further into the underlying cause.
Bonus Read : How to Increase File Upload Size in NGINX
5. Application Bugs
Based on previous step, once you have identified the requested URLs that return 503 service temporarily unavailable error, look for bugs in code or script that serve those URLs. Look into your version control system’s commit history for any recent modifications to the code that serves those URLs. This will help you identify and fix problems quickly.
Hopefully, the above tips will help you fix 503 service temporarily unavailable error in Apache.