Postgres could not connect to server

Question

After I did brew update and brew upgrade, my postgres got some problem. I tried to uninstall postgres and install it again, but it didn't work as well.

This is the error message. (I also got this error message when I try to do rake db:migrate)

$ psql
psql: could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

How can I solve it?

Mac version: Mountain lion.

homebrew version: 0.9.3

postgres version: psql (PostgreSQL) 9.2.1

And this is what I did:

$ brew uninstall postgresql
Uninstalling /usr/local/Cellar/postgresql/9.2.1...
$ brew uninstall postgresql
Uninstalling /usr/local/Cellar/postgresql/9.1.4...
$ psql --version
bash: /usr/local/bin/psql: No such file or directory
$ brew install postgresql
==> Downloading http://ftp.postgresql.org/pub/source/v9.2.1/postgresql-9.2.1.tar.bz2
Already downloaded: /Library/Caches/Homebrew/postgresql-9.2.1.tar.bz2
......
......
==> Summary
/usr/local/Cellar/postgresql/9.2.1: 2814 files, 38M, built in 2.7 minutes
$ initdb /usr/local/var/postgres -E utf8
The files belonging to this database system will be owned by user "laigary".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.UTF-8".
The default text search configuration will be set to "english".

initdb: directory "/usr/local/var/postgres" exists but is not empty
If you want to create a new database system, either remove or empty
the directory "/usr/local/var/postgres" or run initdb
with an argument other than "/usr/local/var/postgres".
$ mkdir -p ~/Library/LaunchAgents
$ cp /usr/local/Cellar/postgresql/9.2.1/homebrew.mxcl.postgresql.plist ~/Library/LaunchAgents/
$ launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
homebrew.mxcl.postgresql: Already loaded
$ pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
server starting
$ env ARCHFLAGS="-arch x86_64" gem install pg
Building native extensions.  This could take a while...
Successfully installed pg-0.14.1
1 gem installed
$ psql --version
psql (PostgreSQL) 9.2.1
$ psql
psql: could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

Now, after I reinstalled homebrew, when I use $ psql, it doesn't show any error message.

But I run rake db:migrate in my Rails app, it shows:

could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/var/pgsql_socket/.s.PGSQL.5432"?

/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1213:in `initialize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1213:in `new'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1213:in `connect'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:329:in `initialize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `new'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `postgresql_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:309:in `new_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:319:in `checkout_new_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:241:in `block (2 levels) in checkout'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:236:in `loop'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:236:in `block in checkout'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:233:in `checkout'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:96:in `block in connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:95:in `connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:404:in `retrieve_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:170:in `retrieve_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:144:in `connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:107:in `rescue in create_database'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:51:in `create_database'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:40:in `block (3 levels) in <top (required)>'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:40:in `each'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:40:in `block (2 levels) in <top (required)>'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:205:in `call'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:205:in `block in execute'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:200:in `each'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:200:in `execute'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:158:in `block in invoke_with_call_chain'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:151:in `invoke_with_call_chain'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:144:in `invoke'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:116:in `invoke_task'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:94:in `block (2 levels) in top_level'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:94:in `each'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:94:in `block in top_level'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:133:in `standard_exception_handling'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:88:in `top_level'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:66:in `block in run'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:133:in `standard_exception_handling'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:63:in `run'
/usr/local/bin/rake:32:in `<main>'
Couldn't create database for {"adapter"=>"postgresql", "encoding"=>"unicode", "database"=>"riy_development", "pool"=>5, "username"=>nil, "password"=>nil}

Finally I've found a solution.

sudo mkdir /var/pgsql_socket/
sudo ln -s /private/tmp/.s.PGSQL.5432 /var/pgsql_socket/

This solution is a little tricky, but it works. Hope anyone has a better solution

Update

This works for me as well.

rm /usr/local/var/postgres/postmaster.pid

Answer 1

Had a similar problem; a pid file was blocking postgres from starting up. To fix it:

$ rm /usr/local/var/postgres/postmaster.pid
$ brew services restart postgresql

and then all is well.

Answer 2

This can sometimes be an issue with a postgres upgrade.

In my case, it happened when upgrading from 9.3 to 9.4.

See http://www.postgresql.org/docs/9.4/static/upgrading.html

OS X/Homebrew:

Try running postgres -D /usr/local/var/postgres -- it will give you a much more verbose output if postgres fails to start.

In my case, running rm -rf /usr/local/var/postgres && initdb /usr/local/var/postgres -E utf8 removed my old databases and then reinitialized the postgres db schema.

Thanks to https://github.com/Homebrew/homebrew/issues/35240 for that solution.

After regenerating my databases (with rake db:create) everything worked fine again.

Answer 3

Found a solution that worked for me here:

https://dba.stackexchange.com/questions/75214/psql-could-not-connect-to-server-no-such-file-or-directory

You basically run the following command to manually start the server:

pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start

Answer 4

If installing and uninstalling postgres with brew doesn't work for you, look at the logs of your postgresql installation or:

postgres -D /usr/local/var/postgres

if you see this kind of output:

LOG:  skipping missing configuration file "/usr/local/var/postgres/postgresql.auto.conf"
FATAL:  database files are incompatible with server
DETAIL:  The data directory was initialized by PostgreSQL version 9.4, which is not compatible with this version 9.6.1.

Then try the following:

rm -rf /usr/local/var/postgres && initdb /usr/local/var/postgres -E utf8

Then start the server:

pg_ctl -D /usr/local/var/postgres -l logfile start

Source

Answer 5

Upgrading the database works for me

brew postgresql-upgrade-database

Answer 6

On Yosemite, if the pid file is blocking Postgres from starting and you have a launchctl daemon trying (and failing) to load the database daemons, then you'll need to unload the plist file:

$ launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

Then remove the pid file

$ rm /usr/local/var/postgres/postmaster.pid

Then reload the launchctl daemon

$ launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

Answer 7

For anyone reading this and using Postgres.app, you may need host: localhost in your database.yml. http://postgresapp.com/documentation#toc_3

Answer 8

brew services start postgres 

worked for me!

Answer 9

The problem can also be attributed to a crashed process that left postmaster.pid file behind. I do this and work's:

$ brew services stop postgresql
$ rm /usr/local/var/postgres/postmaster.pid # adjust path accordingly to your install
$ brew services start postgresql

Answer 10

Check that the socket file exists.

$ ls -l /tmp/.s.PGSQL.5432
srwxrwxrwx  1 you  wheel  0 Nov 16 09:22 /tmp/.s.PGSQL.5432

If it doesn't then check your postgresql.conf for unix_socket_directory change.

$ grep unix_socket /usr/local/var/postgres/postgresql.conf
#unix_socket_directory = ''     # (change requires restart)
#unix_socket_group = ''         # (change requires restart)
#unix_socket_permissions = 0777     # begin with 0 to use octal notation

Answer 11

The problem is because there is already a running service on the port 5432 and we cannot establish psql socket connection through this port.

I removed the socket file

rm -rf /tmp/.s.PGSQL.5432/

Then I reinitialized postgres services

postgres -D /usr/local/var/postgres

This worked for me.

Answer 12

The most fool proof way around this is to do

brew reinstall postgresql

This will keep your user permission etc all intact and everything is reset to new. Works all the time !

Answer 13

This is actually what you are supposed to do:

you should instead look at /usr/local/var/postgres/postmaster.pid

and then look at the first line of the file - this is the bad PID

Run

ps aux | grep <PID>

for example:

ps aux | grep 12345

then do

kill <PID>

for example

kill 12345

Assuming it's still running

https://superuser.com/questions/553045/fatal-lock-file-postmaster-pid-already-exists

do not listen to the accepted answer it is bad and will corrupt your data!!!

Answer 14

Changing postresql or database.yml config settings, changing $PATH, or creating symlinks were all unnecessary for me. All I needed to do was gem uninstall pg and then bundle (or gem install pg).

The issue was that the pg gem had been installed before homebrew postgres, so was picking up the settings from the version of postgres that comes with MacOS. Reinstalling it (and thus rebuilding the native extension) fixed the problem.

Answer 15

This happened to me when I upgraded from 9.3.4 to 9.5 as the databases are incompatible without upgrading.

I used pg_upgrade as follows:

Stop postgres

$ brew services stop postgresql

Upgrade the databases:

$ pg_upgrade \
   -d /usr/local/var/postgres \
   -D /usr/local/var/postgres9.5 \
   -b /usr/local/Cellar/postgresql/9.3.4/bin/ \
   -B /usr/local/Cellar/postgresql/9.5.0/bin/ \
   -v

Archive the old databases:

 $ mv /usr/local/var/postgres /usr/local/var/postgres9.3.save
 $ mv /usr/local/var/postgres9.5 /usr/local/var/postgres

Restart postgres:

 $ brew services start postgresql

Updated Gems (for rails / active record) :

 $ gem uninstall pg
 $ gem uninstall activerecord-postgresql-adapter
 $ bundle install

Answer 16

If postgres was installed using homebrew, you can fix this by running:

brew link postgres

Answer 17

Psql option

-h hostname --host=hostname

: Specifies the host name of the machine on which the server is running. If the value begins with a slash, it is used as the directory for the Unix-domain socket.

$ grep "port\|unix_socket" /etc/postgresql/9.1/main/postgresql.conf
port = 5433                                         # (change requires restart)
unix_socket_directory = '/var/run/postgresql'       # (change requires resta

$ netstat -nalp | grep postgres
unix  2      [ ACC ]     STREAM     LISTENING     106753   4349/postgres       /tmp/.s.PGSQL.5432
unix  2      [ ACC ]     STREAM     LISTENING     10377 1031/postgres       /var/run/postgresql/.s.PGSQL.5433

Run psql with -host Option

$ psql -p 5433 -h /var/run/postgresql

No need to make a soft link

Answer 18

Came across this issue too on MacOS Sierra and when we ran pg_ctl as described above we then had the following error pg_ctl: no database directory specified and environment variable PGDATA unset. So we followed the steps here which solved our issue, namely:

mkdir ~/.postgres

initdb ~/.postgres

pg_ctl -D ~/.postgres start

Answer 19

I got same issue because I'm using a wrong Postgres's username in code. I logged into postgres psql -d postgres and enter \du to take role name and correct Postgres's username.

So when you guys face this issue, you guys need to make sure you're using correct Postgres username, password, hostname and database...

Hope this will help anyone

Answer 20

This worked for me (as a mix of previous answers):

$ rm /usr/local/var/postgres/postmaster.pid

$ pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start

Source: https://coderwall.com/p/zf-fww/postgres-on-osx-with-homebrew-not-running-after-osx-crash

Answer 21

If you shut down your system without quitting psql, postgres would not have removed some files.

I didn't find the file postmaster.pid in the location usr/local/var/postgres

So I did the below:

brew services start postgresql

The above command should let you start postgres

Answer 22

I faced the same problem for psql (PostgreSQL) 9.6.11.

what worked for me -

remove postmaster.pid -- rm /usr/local/var/[email protected]/postmaster.pid

restart postgres -- brew services restart [email protected]

If this also doesn't work then run -- sudo chmod 700 /usr/local/var/[email protected]

Answer 23

I ran into this issue after trying to restore/drop/create a db while other processes were accessing them. MacOSX/Homebrew fix was:

1. close all other accessing processes rails server, rails console, guard, etc...
2. load/unload using the commands found in brew info postgres
3. run restore/drop/create from before

Answer 24

FWIW this happened to me today, but what happened was that I was running Ubuntu updates at the time, which were likely updating Postgres. Once the update completed, I was able to connect without a hitch.

For completeness' sake, I was trying to retrieve records from the database from a Rails console:

development (main):0 > a = MyModel.find 73694
PG::ConnectionBad: 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"?

Answer 25

It looks like your psql doesn't run. You should run it before connect. You can do that using Postgres.app for Mac OS only. (Download and install this app http://postgresapp.com) Open the app, and you have a PostgreSQL server ready and awaiting new connections. Close the app, and the server shuts down. You also can find this info here http://www.postgresql.org/download/macosx/. Hope this will help you.

Answer 26

It is because a previous server a still running, try closing everything down and re-running your application.

Answer 27

For those who use this command and doesn't work or the file is not there and are using Ruby on Rails

rm /usr/local/var/postgres/postmaster.pid

Or any other command and just keep on failing.

I solved this problem uninstalling with Brew. I had to uninstall with brew 2 times, because at the first uninstall there will remain another version of postgresql, with the second uninstall the process will be completed.

Install postgresql with Brew

Then drop, create and migrate the data bases of the project

(Don't forget to start the postgresql server)

Answer 28

¿Are you recently changed the pg_hba.conf? if you did just check for any typo in:

"local" is for Unix domain socket connections only

local all all password

IPv4 local connections:

host all all 127.0.0.1/32 password

IPv6 local connections:

host all all ::1/128 password

Sometimes a simple mistake can give us a headache. I hope this help and sorry if my english is no good at all.

Answer 29

This happens when postgres server is not running. Steps to properly install Postgres via Homebrew on MAC :

1. brew install postgres

2. initdb /Users/<username>/db -E utf8 [This initializes postgres to use the given directory as the database directory. Normally it is not adviced to use the user directory for database storage. Edit sudoers file to add initdb and similar commands and then run initdb on /usr/local/var/postgres]

3. pg_ctl -D /Users/<username>/db -l logfile start [After getting success with step 2 it will prompt to run step 3. This command manually starts the server.]

Answer 30

In my case, the trouble was caused by Mac OS updating. Upgrading PostgreSQL solved the issue.

# upgrade database version solved the trouble
$ brew postgresql-upgrade-database

However, this error is quite common and has multiple possible reasons, you shouldn’t fully rely on my solution above.