MySQL error
Ow, hey! We can't connect to the database!
Like you see there is an error, well, if not: suprise! So, let's take a look at it...

What for error is this?
This is a MySQL Database Connect error, that means that that one or more files couldn't find on the server. Maybe removed by accedent? At the bottom of the page there are the page name(s) we can't find, and you can report or fix this. Does the page exits? Ow? Fail? Hmm, check if the page name is 100% correct, and don't forgot to put there some functions and variables in ;).

What went wrong?
This is the MySQL that appears:
Access denied for user 'root'@'localhost' (using password: NO)

Access denied error?
That means that the CMS wasn't able to connect to the database, because you filled the wrong user information (like serverIP(domain/subdomain/IP/localhost) password, username or database), the CMS need this information to load the database.

Getaddrinfo failed?
'What the ****' you fink? Yeah, me first too, but it means the CMS can't connect to the host, check if you filled the right IP, domain, subdomain, localhost or something like that. By the way, it means that this host is unknown (does not exist). Maybe the website is (temporarily) offline?

Can not connect because the target machine actively refused the connection?
Yeah, and this means that MySQL (port 3306) isn't open (or used). Check your computer (or VPS) if your Xampp, MySQL server or something else is started, and no other programm uses port 3306. If so, close that program, en try reload the SQL server.

What now?
If this error that always appears, contact an administrator.