Are you seeing the 'Error establishing a database connection' notice on your WordPress website? It is a fatal error that makes your WordPress website inaccessible to the users.
This error occurs when WordPress is unable to connect to the database. A number of things can affect your WordPress database connection which makes it a bit difficult for beginners to troubleshoot.
How to Fix a 500 Internal Server Error on a WordPress-Hosted Site
The 500 Internal Server Error is a very general HTTP status code that means something has gone wrong on a website’s server, but the server does not get any more specific on what the actual problem is.
Websites phrase 500 errors in many ways, but they’re all basically saying the same thing: there’s a general server issue going on right now.