Wordpress says Error Establishing DB connection Error

Hi,

I have a serious trouble with my wordpress site.
I am hositng it by my self on AWS linux. My site says Error establishing DB connection when eevr I reeive 30+ visitors its gave me this message.
I resolve it by restarting my EC2 instance

but for last 3 days restarting that is not working either.

Have any one faces this trouble ??
Pleas help me resolve the issue

Refer this article to resolve the issue: http://www.wpbeginner.com/wp-tutoria...-in-wordpress/

Seems your my.cnf or mysql configuration is wrong or need to increase limitation.

Or other reason is firewall or server setting which automatically kill mysql process If use more than x amount or memory.

For instance, it can be because of the wrong login username and password being used to access the admin panel. If the login credentials have changed recently, you will not be able to access your database with the old ones. So your first order of business should be to confirm that the login credentials you’re entering are accurate.