Ubuntu 18.04 as Windows bash Distributor ID: Ubuntu Description: Ubuntu 18.04.1 LTS Release: 18.04 Codename: bionic PG 10.5.1 postgres@ravi-lenovo:~$ psql -d postgres psql (10.5 (Ubuntu 10.5-1.pgdg16.04+1)) A CREATE DATABASE statement spewed out WARNING: could not flush dirty data: Function not implemented many times, but the db was created. What exactly is this? A simple search tells that this is an old problem and my Windows has necessary WSL and other subsystem for this error to not show up.