First we start with user binding limit.
check if you have a section lines similar to:
* hard nofile SOMENUMBER
if you do change it to something like or append if part is missing:
* hard nofile 750000
* soft nofile 750000
root hard nofile 750000
root soft nofile 750000
note: after changing the file you will need to re-login for changes to take effect. Remember that application might be using different user.
change / append following value:
fs.file-max = 2097152
run sysctl -p after saving the file.
what is the difference?
file-max is the maximum File Descriptors (FD) enforced on a kernel level, which cannot be surpassed by all processes without increasing. The ulimit is enforced on a process level, which can be less than the file-max.