Symptoms
- Plesk Obsidian running on a Linux-based operating system
- Unable to access website the website example.com with 502 Bad Gateway or 503 Service Temporarily Unavailable errors showing in a browser
- The following error can be found in the log file for the PHP version that this website is configured to use (for example
/var/log/plesk-php74-fpm/error.log):WARNING: [pool example.com] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 0 idle, and 129 total children
- The Apache error log for the website
/var/www/vhosts/example.com/logs/example.com/error_logcontains an error that is similar to the following:AH01067: Failed to read FastCGI header, referer: https://example.com/testpage.php
Cause
Some or all values for the PHP FastCGI Process Manager (PHP-FPM) directives below were exceeded by the related website:
- pm.start_servers
- pm.min_spare_servers
- pm.max_spare_servers
Resolution
Apply one of the solutions below:
Solution I
- Log into Plesk.
- Go to Domains > example.com > PHP Settings > PHP-FPM settings section.
- Change pm from dynamic to ondemand:
-
Press the OK button to apply the hcnage
Note: after applying the steps above, the RAM consumption and load on the server can be increased
Solution II
- Log into Plesk.
- Go to Domains > example.com > PHP Settings > PHP-FPM settings section.
- Increase values for the directives pm.start_servers, pm.min_spare_servers, pm.max_spare_servers and press the OK button to apply the changes: