Solution how to fix following error generated in /var/log/syslog by mysqld service on Ubuntu 16.04 with MariaDB 10.0.x:
mysqld: 181210 [ERROR] Error in accept: Too many open files
If you see message above you probably reached default limits of mysqld service. To set open files parameter limit as unlimited, follow steps below:
Fast tutorial how to install into ISPConfig 3.1 Additional PHP Versions without compiling from sources.
Note: There is official tutorial on howtoforge.com but from my point of view is so complicated and each time you need to compile new PHP version or additional PHP extensions. That’s the reason why repository is the best choice and super easy to setup in this tutorial instead of compiling PHP from sources.