Apache sometimes crashes, outcome from the Apache error_log strike this error.
(22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex (22)Invalid argument: couldn't grab the accept mutex
Generally, these type of errors happen on systems low on memory or file handlers.
In a couple of cases enabling piped logging via “WHM Home » Service Configuration » Apache Configuration » Piped Log Configuration” can resolve this issue.
Other suggested resolution for the error message would be to try adding the following line to/usr/local/apache/conf/httpd.conf
AcceptMutex fcntl
After doing that Run apache distiller
/usr/local/cpanel/bin/apache_conf_distiller –update –main /scripts/rebuildhttpdconf /etc/init.d/httpd graceful