A few days ago, I was doing some changes on my site, and suddenly it went out with words: “Database connection failed!”, I was so surprised! But after the rebooting my server, it started to work, like nothing happened! But by my experience, I was sure, that it will happen again!  So, I was very curious and I opened the MySQL logs, there were more than 5000 lines, but happily, I found the information about the server crash and it was something like that:

Of course, I’ve started to google that error and I found the solution! To fix it, you need to go to: /etc/mysql/conf.d/ , and create file my.cnf, then you need to put that code into the file:

max_connections = 50
max_user_connections  = 10
innodb_buffer_pool_size = 32M 

After all of the changes, you need to reboot your MySQL server!

Now it should work. You can see the difference only on when you will have a lot of traffic on the server, or after some time!