Maximum file limit has been reached on your server.
Please refer the following steps to rectify the above issue.
Login into server as a root and edit the file called /etc/sysctl.conf
Add the line there as follows:
fs.file-max = 22992
Save and exit from the file.
In order to apply these changes execute the command:
# sysctl –p
This will increase the maximum number of open files for your system.