I had an error tailing my web logs, like this:

==> test.jj5.net-error.log <==
tail: inotify resources exhausted
tail: inotify cannot be used, reverting to polling

I found tail: “inotify resources exhausted” and/or “inotify cannot be used, reverting to polling: Too many open files” which said to edit /etc/sysctl.conf with:

# 2017-05-03 jj5 - SEE: tail inotify resources exhausted:
# https://nefaria.com/2014/08/tail-inotify-resources-exhausted/

Then to apply the new settings:

# sysctl -p