On a Ubuntu 16.04 server running MySQL 5.7.7 or higher, the default Plesk backup might show a database warning: plesk (Errcode: 24 – Too many open files) when using LOCK TABLES.
This is quite easy to fix. Login to the server via SSH and perform the following operations:
- create a folder mysql.service.d in /etc/systemd/system/
- create a file override.conf and edit the content
- add the following setting inside the override.conf file and save it with :wq
- reload the changed configuration and restart mysql
sudo systemctl daemon-reload sudo systemctl restart mysql
Next thing is to perform a test backup and you are all done.