Fix the PHP-FPM Server Reached Max_children Error

Occasionally, you may run into an error with the PHP-FPM server:

[10-Dec-2018 04:30:31] WARNING: [pool example1] server reached max_children setting (5), consider raising it 

This can be fixed by typically making a change to the php-fpm.conf file, but you should also check for the other possible causes of that error. As PHP-FPM is a part of the UltraStack configuration, you will normally only see this error with that configuration in place (unless you have configured your server to use PHP-FPM). This article discusses the typical causes of this error and how to change the value within the configuration file.

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Causes of the error

There can be a number of reasons that this error will occur. You should always check your server’s performance and resource usage to help prevent errors. The typical causes of this error include:

  • High traffic (concurrent visitors)
  • Bad scripts or code that leads to slow execution of PHP code
  • Low settings for the max_children setting in the PHP-FPM Config

As resource usage may often be the cause to this problem, make sure that your server has been properly optimized and tuned. A good guide for this topic is the WordPress Stack Optimization Guide: Tuning for VPS & Dedicated Servers.

Increase Max Children

In order to make changes to the configuration for PHP-FPM you will need to have at least a VPS subscription. Shared server resellers will need to submit a support ticket for changes to the configuration.

  1. Login to WHM
  2. In the search field in the top left corner, type in MultiPHP Manager
  3. Click on the System PHP-FPM Configuration tab
  4. Increase Max children as needed. It starts at 5 by default.

When you log in to WHM and open the MultiPHP Manager you will see the screen as per the image below:

multi php manager
Change the Max Children value

When you have completed adjusting the value for Max Children, make sure to scroll to the bottom of the screen and click on Save Configuration.

If you are unsure of the proper value, contact our live technical support team or submit a support ticket. For more information, see our other UltraStack tutorials.

Arnel Custodio Technical Writer; WordPress Contributor & Volunteer

As a writer for InMotion Hosting, Arnel has always aimed to share helpful information and provide knowledge that will help solve problems and aid in achieving goals. He's also been active with WordPress local community groups and events since 2004.

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