Nginx errors "Too many files open"


I have moved a Drupal 8 site from my development server to (temporary) production server.

Everything else is working the same as in development, but the nginx fails quite often with socket failed “24: Too many open files while connecting to upstream” and shows error 500 to the client. On development server I haven’t seen anything like that during last few weeks while developing the site.

I have the same architecture in both servers (centos 7, nginx) and also the same nginx conf files, can’t figure out what’s the difference.
I have tried to locate this from Internet but to no avail so far.

Could anyone give any suggestions? The site should be up very soon (like tomorrow – whole project was started late but the deadline didn’t move – of course) and I feel really frustrated with this as I just thought I could accomplish the almost impossible timetable.



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