I was running word press for 4 months with no problem and all of the sudden I get this same problem as you guys are having.
I contacted my web hosting servicer and they said “Hello, The problem was on our side, there was a misconfiguration of the DB Server. Accept our apologies for any caused inconvenience.” They ended up fixing the DB Server (if that was the problem) yesterday BUT today I am having the same problem.
I have not changed the user name, passwrd, or host address from my admin file therefore I dont see how it could be a misconfiguration from my part.
I know my web hosting told me it was their fault but I cannot wait days for them to finally fix it correctly. Any ideas??