"Error establishing a database connection" error

So, I went to my site and came into an “Error establishing a database connection” error.

It started with this page…

WordPress_Database_Error_Old_Issue_Screenshot_09152020

…now it’s at this page…

WordPress_Database_Error_New_Issue_Screenshot_09152020

Any help with this issue will be appreciated.

Looks like the site is running now. What was the fix?

In the second screenshot, it appears to be an URL-doubling typo (vanndigital.comwww.vanndigital.com), so DNS lookup fails.