could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432
// In my case PostgreSQL updates from version 13.4 to 14 in background, so it fixes by:
brew postgresql-upgrade-database
// In other case the problem fixed by:
rm -rf /usr/local/var/postgres/postmaster.pid
// Restart service postgresql:
brew services restart postgresql
// How can you understand what is the problem?
// For first see what service is not correct started:
brew services list
// For second show file postgres.log, where will be the error:
tail -f /usr/local/var/log/postgres.log
// And so find answer by this error's text