How to Fix “upstream timed out (110: Connection timed out) while reading response header from upstream” in NGINX

How to Fix upstream timed out Error in Nginx

When managing a website, encountering errors is part of the process. One such error that you may come across when using the Nginx server is the “upstream timed out (110: Connection timed out) while reading response header from upstream”.

[root@vps ~]# tail -f /var/log/nginx/whgeeks-api.com.error.log

2022/12/14 15:33:15 [error] 1040#0: *52134 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 127.0.0.1

This error typically occurs when Nginx is unable to get a response from an upstream server within a specified time frame.

Nginx is a high-performance HTTP server and reverse proxy server. It is known for its stability, rich feature set, simple configuration, and low resource consumption. Nginx is used by many of the world’s most visited websites and is an excellent choice for any dedicated, VPS, or cloud hosting environment.

In this comprehensive guide, we will walk you through the steps to troubleshoot and fix this error. We will also provide a brief overview of what Nginx is and why it’s one of the best web servers available today.

What Causes the “upstream timed out” Error?

The “upstream timed out” error in Nginx is typically caused by slow processing times on the upstream server. This could be due to a variety of reasons, and we’ll delve into each one in more detail below:

1. High Server Load

One of the most common causes of the “upstream timed out” error is high server load. When the server is overloaded with requests, it may struggle to process them all in a timely manner. This can be due to a sudden surge in traffic, a DDoS attack, or simply because the server’s resources are not sufficient to handle the number of requests it’s receiving.

For example, if your website suddenly gets featured on a popular news site, the influx of visitors can overload your server, causing slow response times and potentially leading to the “upstream timed out” error.

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2. Slow Database Queries

Another common cause of this error is slow database queries. If your website relies heavily on database interactions, such as a dynamic website built with a CMS like WordPress, slow database queries can significantly slow down the response time of your server.

For instance, if a query is poorly optimized and takes a long time to retrieve data from the database, it can cause a delay in the server’s response. This delay might exceed the timeout value set in Nginx, triggering the “upstream timed out” error.

3. Slow Network Connections

Slow network connections between the Nginx server and the upstream server can also lead to this error. Network latency, packet loss, or network congestion can slow down the communication between these servers, causing delays in response times.

For example, if your Nginx server is located in New York and your upstream server is in Tokyo, the physical distance and network conditions between these two locations can cause a delay in the communication. If this delay exceeds the timeout value set in Nginx, it can result in the “upstream timed out” error.

How to Fix the “upstream timed out” Error

Step 1: Identify the Cause

The first step in fixing the “upstream timed out” error is to identify the cause. Check the server logs to see if there are any indications of high server load or slow processing times. If the server load is high, you may need to upgrade your server or optimize your server configuration.

Step 2: Increase the Timeout Value

If the server load is not the issue, the next step is to increase the timeout value in the Nginx configuration. The default timeout value is typically 60 seconds, but you can increase this to a higher value if necessary.

To do this, open the Nginx configuration file in a text editor:

sudo nano /etc/nginx/nginx.conf

Find the http block and add the following line:

proxy_read_timeout 120;

This will increase the timeout value to 120 seconds. Save and close the file, then restart Nginx to apply the changes:

sudo systemctl restart nginx

Step 3: Optimize the Upstream Server

If increasing the timeout value doesn’t resolve the issue, the problem may lie with the upstream server. You may need to optimize the upstream server to reduce processing times. This could involve optimizing database queries, reducing server load, or improving network connections.

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Step 4: Check Network Connections

If the upstream server is not the issue, the problem could be due to slow or unstable network connections. Check the network connections between the Nginx server and the upstream server. If there are any issues, you may need to contact your network provider or investigate further to identify and resolve the issue.

Step 5: Consult with a Professional

If you’ve tried all the above steps and are still experiencing the “upstream timed out” error, it may be time to consult with a professional. A professional with experience in Nginx and server administration can help identify and resolve complex issues that may be causing the error.

Commands Mentioned

  • sudo nano /etc/nginx/nginx.conf – Opens the Nginx configuration file in a text editor.
  • proxy_read_timeout 120; – Increases the timeout value to 120 seconds.
  • sudo systemctl restart nginx – Restarts Nginx to apply the changes.

FAQs

  1. What is the “upstream timed out” error in Nginx?

    The “upstream timed out” error in Nginx typically occurs when Nginx is unable to get a response from an upstream server within a specified time frame. This could be due to slow processing times on the upstream server, high server load, or slow network connections.

  2. How can I increase the timeout value in Nginx?

    You can increase the timeout value in Nginx by editing the Nginx configuration file. Add the line ‘proxy_read_timeout 120;’ to the ‘http’ block to increase the timeout value to 120 seconds. Save and close the file, then restart Nginx to apply the changes.

  3. What can cause slow processing times on the upstream server?

    Slow processing times on the upstream server can be caused by a variety of factors, including high server load, slow database queries, or slow network connections. Optimizing these areas can help reduce processing times and prevent the “upstream timed out” error.

  4. How can I optimize the upstream server?

    Optimizing the upstream server can involve a variety of strategies, including optimizing database queries, reducing server load, or improving network connections. The specific strategies will depend on the cause of the slow processing times.

  5. When should I consult with a professional?

    If you’ve tried identifying the cause, increasing the timeout value, optimizing the upstream server, and checking network connections, but are still experiencing the “upstream timed out” error, it may be time to consult with a professional. A professional with experience in Nginx and server administration can help identify and resolve complex issues that may be causing the error.

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Conclusion

The “upstream timed out (110: Connection timed out) while reading response header from upstream” error in Nginx can be a frustrating issue to deal with, but with the right knowledge and tools, it can be resolved. By identifying the cause, increasing the timeout value, optimizing the upstream server, and checking network connections, you can troubleshoot and fix this error.

Remember, it’s always important to monitor your server’s performance and load to prevent such issues from occurring. And if you’re still having trouble, don’t hesitate to consult with a professional. They can provide real expert guidance and help you ensure your Nginx-powered machine is running smoothly and efficiently.

Hope this guide has been helpful in resolving your issue.

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