I faced Same error

I fixed it by creating a new user in postgresSQL
after that you need to edit odoo.conf file with a new user data

for future reference, i had to put spanish latino america in language, because another variation of spanish does not work. for me it worked.

Hi I am running odoo16
my server was working fine but out of nowhere i started getting this error upon database creation. My postgres is latest version and i also updated my odoo source code but i am still facing the error. 
Someone please give me a solution.