Error: [error] server reached MaxClients setting, consider raising the MaxClients setting


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You need to modify /etc/httpd/conf.d/swtune.conf in the container holding Plesk. It has configuration directives which override /etc/httpd/conf/httpd.conf. You must restart apache to make the changes take effect.
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Fix:
vi /etc/httpd/conf.d/swtune.conf
MaxClients from 10 to 10000

Also Consider the value from the
/etc/httpd/conf/httpd.conf
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#service httpd stop
#service httpd start
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This should fix the issue.