This is a living document. Everything in this document is made in good faith of being accurate, but like I just said; we don't yet know everything about what's going on.
Update: I've disabled comments as of 2025-01-26 to avoid everyone having notifications for something a year on if someone wants to suggest a correction. Folks are free to email to suggest corrections still, of course.
| After automatically updating Postgres to 10.0 via Homebrew, the pg_ctl start command didn't work. | |
| The error was "The data directory was initialized by PostgreSQL version 9.6, which is not compatible with this version 10.0." | |
| Database files have to be updated before starting the server, here are the steps that had to be followed: | |
| # need to have both 9.6.x and latest 10.0 installed, and keep 10.0 as default | |
| brew unlink postgresql | |
| brew install [email protected] | |
| brew unlink [email protected] | |
| brew link postgresql |
The connection failed because by default psql connects over UNIX sockets using peer authentication, that requires the current UNIX user to have the same user name as psql. So you will have to create the UNIX user postgres and then login as postgres or use sudo -u postgres psql database-name for accessing the database (and psql should not ask for a password).
If you cannot or do not want to create the UNIX user, like if you just want to connect to your database for ad hoc queries, forcing a socket connection using psql --host=localhost --dbname=database-name --username=postgres (as pointed out by @meyerson answer) will solve your immediate problem.
But if you intend to force password authentication over Unix sockets instead of the peer method, try changing the following pg_hba.conf* line:
from
This guide assumes that you recently run brew upgrade postgresql and discovered to your dismay that you accidentally bumped from one major version to another: say 9.3.x to 9.4.x. Yes, that is a major version bump in PG land.
First let's check something.
brew info postgresqlThe top of what gets printed as a result is the most important: