Upon restarting my Mac I got the dreaded Postgres error:
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
The reason this happened is because my macbook froze completely due to an unrelated issue and I had to do a hard reboot using the power button. After rebooting I couldn't start Postgres because of this error.
When connecting to Postgres you might see this error: psql: could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket <some socket> . This happens most often when Postgres' server daemon process is not running.
The default username for postgres is postgres. (If you are using Advanced Server it is enterprisedb.) On a Mac or Windows, you are able to connect to the default instance by simply hitting enter at the shell or command prompt when trying to run psql and keying in the password.
It is better to use another method like using psql to run a simple query and checking the exit code, e.g. psql -c 'SELECT 1' , or use pg_isready to check the connection status. psql -c "SELECT 1" -d {dbname} > /dev/null || postgres -D /usr/local/var/postgres >postgres.
WARNING: If you delete postmaster.pid without making sure there are really no postgres
processes running you, could permanently corrupt your database. (PostgreSQL should delete it automatically if the postmaster has exited.).
SOLUTION: This fixed the issue--I deleted this file, and then everything worked!
/usr/local/var/postgres/postmaster.pid
--
and here is how I figured out why this needed to be deleted.
I used the following command to see if there were any PG processes running. for me there were none, I couldn't even start the PG server:
ps auxw | grep post
I searched for the file .s.PGSQL.5432 that was in the error message above. i used the following command:
sudo find / -name .s.PGSQL.5432 -ls
this didn't show anything after searching my whole computer so the file didn't exist, but obviously psql
"wanted it to" or "thought it was there".
I took a look at my server logs and saw the following error:
cat /usr/local/var/postgres/server.log
at the end of the server log I see the following error:
FATAL: pre-existing shared memory block (key 5432001, ID 65538) is still in use
HINT: If you're sure there are no old server processes still running, remove the shared memory block or just delete the file "postmaster.pid".
Following the advice in the error message, I deleted the postmaster.pid file in the same directory as server.log. This resolved the issue and I was able to restart.
So, it seems that my macbook freezing and being hard-rebooted caused Postgres to think that it's processes were still running even after reboot. Deleting this file resolved. Hope this helps others! Lots of people have similar issues but most the answers had to do with file permissions, whereas in my case things were different.
None of the above worked for me. I had to reinstall Postgres the following way :
Uninstall postgresql with brew : brew uninstall postgresql
brew doctor
(fix whatever is here)
brew cleanup
Remove all Postgres folders :
rm -r /usr/local/var/postgres
rm -r ~/Library/Application\ Support/Postgres
Reinstall postgresql with brew : brew install postgresql
Start server : brew services start postgresql
You should now have to create your databases... (createdb
)
If you're on macOS and installed postgres via homebrew, try restarting it with
brew services restart postgresql
If you're on Ubuntu, you can restart it with either one of these commands
sudo service postgresql restart
sudo /etc/init.d/postgresql restart
Maybe this is unrelated but a similar error appears when you upgrade postgres
to a major version using brew
; using brew info postgresql
found out this that helped:
To migrate existing data from a previous major version of PostgreSQL run:
brew postgresql-upgrade-database
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