This is an error which is usually thrown by the server when there is a failure to start apache. The above description can be found in the error logs of the server.

Solutions:

Step 1: Open file /etc/init.d/httpd OR /usr/sbin/apachectl

Step 2: Add `ulimit -n 65536`

{The error usually occurs due to the lower number of file descriptors.}

To check the limit of file descriptors over the server described within the file /proc/sys/fs/file-max, run the following command:

# cat /proc/sys/fs/file-max
1024

If the value found in fs.file-max small, you must increase it by running the following command:

# echo “65535″ > /proc/sys/fs/file-max

To save these settings for future reboots to keep the values, you may add it to the file /etc/sysctl.conf.

# Maximum number of open files permitted
fs.file-max = 65535

To load new values from the sysctl.conf file, run:

# sysctl -p /etc/sysctl.conf

Now you must restart httpd service by running the following command:

/etc/init.d/httpd restart