Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432?

Question

Before anything, please note that I have found several similar questions on Stack Overflow and articles all over the web, but none of those helped me fix my issue:

• PG Error could not connect to server: Connection refused Is the server running on port 5432?
• PG::ConnectionBad - could not connect to server: Connection refused
• psql: could not connect to server: Connection refused

Now, here is the issue:

• I have a Rails app that works like a charm.
• With my collaborator, we use GitHub to work together.
• We have a master and an mvp branches.
• I recently updated my git version with Homebrew (Mac).
• We use Foreman to start our app locally.

Now, when I try to launch the app locally, I get the following error:

PG::ConnectionBad at /
could not connect to server: Connection refused
    Is the server running on host "localhost" (::1) and accepting
    TCP/IP connections on port 5432?
could not connect to server: Connection refused
    Is the server running on host "localhost" (127.0.0.1) and accepting
    TCP/IP connections on port 5432?

I tried to reboot my computers several times.

I also checked the content of /usr/local/var/postgres :

PG_VERSION      pg_dynshmem     pg_multixact    pg_snapshots    pg_tblspc       postgresql.conf
base            pg_hba.conf     pg_notify       pg_stat         pg_twophase     postmaster.opts
global          pg_ident.conf   pg_replslot     pg_stat_tmp     pg_xlog         server.log
pg_clog         pg_logical      pg_serial       pg_subtrans     postgresql.auto.conf

As you can see, there is no postmaster.pid file in there.

Any idea how I could fix this?

Answer 1

run postgres -D /usr/local/var/postgres and you should see something like:

 FATAL:  lock file "postmaster.pid" already exists
 HINT:   Is another postmaster (PID 379) running in data directory "/usr/local/var/postgres"?

Then run kill -9 PID in HINT

And you should be good to go.

Answer 2

You most likely ran out of battery and your postgresql server didn't shutdown correctly.

The easiest workaround is to download the official postgresql app and launch it: it will force the server to start ( http://postgresapp.com/ )

Answer 3

Most likely it's because your system shutdown unexpectedly

Try

postgres -D /usr/local/var/postgres

You might see

FATAL: lock file "postmaster.pid" already exists HINT: Is another postmaster (PID 449) running in data directory "/usr/local/var/postgres"?

Then try

kill -9 PID

example

kill -9 419

And it should start postgres normally

Answer 4

The postgresql server might be down and the solution might be as simple as running:

sudo service postgresql start

which fixed the issue for me.

Answer 5

This could be caused by the pid file created for postgres which has not been deleted due to unexpected shutdown. To fix this, remove this pid file.

1. Find the postgres data directory. On a MAC using homebrew it is /usr/local/var/postgres/ , other systems it might be /usr/var/postgres/

2. Remove pid file by running:

    rm postmaster.pid

3. Restart postgress. On Mac, run:

    brew services restart postgresql

Answer 6

I had almost just as same error with my Ruby on Rails application running postgresql(mac). This worked for me:

brew services restart postgresql

Answer 7

This worked in my case:

brew uninstall postgresql
rm -fr /usr/local/var/postgres/
brew install postgresql

Answer 8

I resolved the issue via this command

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

At times, you might get this error

pg_ctl: another server might be running; trying to start server anyway

So, try running the following command and then run the first command given above.

pg_ctl -D /usr/local/var/postgres stop

Answer 9

如果要在 Linux 上重新启动 Postgresql，则必须使用以下命令。

/etc/init.d/postgresql restart

Answer 10

This worked for me: run

sudo lsof -i :<port_number>

after that it will display the PID which is currently attached to the process.

After that run sudo kill -9 <PID>

if that doesn't work, try the solution offered by user8376606 it would definitely work!

Answer 11

First I tried

lsof -wni tcp:5432 but it doesn't show any PID number.

Second I tried

Postgres -D /usr/local/var/postgres and it showed that server is listening.

So I just restarted my mac to restore all ports back and it worked for me.

Answer 12

For Docker users: In my case it was caused by excessive docker image size. You can remove unused data using prune command:

docker system prune --all --force --volumes

Warning: as per manual ( docker system prune --help ):

This will remove:

• all stopped containers
• all networks not used by at least one container
• all dangling images
• all dangling build cache

Answer 13

In my case

1. I have changed the port in postgresql.conf file
2. and restart postgresql services in

Run => service.msc => Restart

3. now retry

Answer 14

I encountered a similar problem when I was trying to connect my Django application to PostgreSQL database.

I wrote my Dockerfile with instructions to setup the Django project followed by instructions to install PostgreSQL and run Django server in my docker-compose.yml .

I defined two services in my docker-compose-yml .

services:
  postgres:
    image: "postgres:latest"
    environment:
      - POSTGRES_DB=abc
      - POSTGRES_USER=abc
      - POSTGRES_PASSWORD=abc
    volumes:
      - pg_data:/var/lib/postgresql/data/
  django:
    build: .
    command: python /code/manage.py runserver 0.0.0.0:8004
    volumes:
      - .:/app
    ports:
      - 8004:8004
    depends_on:
      - postgres 

Unfortunately whenever I used to run docker-compose up then same err. used to pop up.

And this is how my database was defined in Django settings.py .

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'abc',
        'USER': 'abc',
        'PASSWORD': 'abc',
        'HOST': '127.0.0.1',
        'PORT': '5432',
        'OPTIONS': {
            'client_encoding': 'UTF8',
        },
    }
} 

So, In the end I made use of docker-compose networking which means if I change the host of my database to postgres which is defined as a service in docker-compose.yml will do the wonders.

So, Replacing 'HOST': '127.0.0.1' => 'HOST': 'postgres' did wonders for me.

After replacement this is how your Database config in settings.py will look like.

DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.postgresql',
            'NAME': 'abc',
            'USER': 'abc',
            'PASSWORD': 'abc',
            'HOST': 'postgres',
            'PORT': '5432',
            'OPTIONS': {
                'client_encoding': 'UTF8',
            },
        }
    } 

Answer 15

1. Find postgresql@10 service directory

  $ ls /usr/local/var/postgresql@10

2. Find file postmaster.pid and delete that file

  $ rm -f postmaster.pid

3. Restart postgres service using

  $ brew services restart postgresql@10

Answer 16

我在windows上经常遇到这个问题，我解决这个问题的方法是Service——点击PostgreSQL Database Server 8.3——点击第二个标签“登录”——选择第一行“本地系统账户”。

Answer 17

It also gives the same error if you just stop your PostgreSQL app. You just need to start it again. (PostgreSQL 11)

Answer 18

I have faced the same issue and I was unable to start the postgresql server and was unable to access my db even after giving password, and I have been doing all the possible ways.

This solution worked for me,

For the Ubuntu users: Through command line, type the following commands:

1.service --status-all (which gives list of all services and their status. where "+" refers to running and "-" refers that the service is no longer running)

check for postgresql status, if its "-" then type the following command

2.systemctl start postgresql (starts the server again)

refresh the postgresql page in browser, and it works

For the Windows users:

Search for services, where we can see list of services and the right click on postgresql, click on start and server works perfectly fine.

Answer 19

Step 1:

cd /etc/postgresql/12/main/

open file named postgresql.conf

sudo nano postgresql.conf

add this line to that file

listen_addresses = '*'

then open file named pg_hba.conf

sudo nano pg_hba.conf

and add this line to that file

host  all  all 0.0.0.0/0 md5

It allows access to all databases for all users with an encrypted password

restart your server

sudo /etc/init.d/postgresql restart

Answer 20

就我而言，我忘记将数据库从 postgres（在我的生产中）更改回我用于开发的 sqlite3。

Answer 21

It's working for me >>Node.Js App

user@MacBook-Pro % sudo lsof -i :5430

Output

COMMAND PID user FD TYPE DEVICE SIZE/OFF NODE NAME

node 7885 user 21u IPv6 0x2e7d89f6118f95b9 0t0 TCP *:radec-corp (LISTEN)

Kill the PID

user@MacBook-Pro % sudo kill -9 7885

One more test

user@MacBook-Pro % sudo lsof -i :5430

user@MacBook-Pro % "No more running PID for the port 5430"

Answer 22

This is how I solved my problem:

see the status of services

brew services list

and the output was :

Name       Status  User Plist
postgresql error   myuser /Users/myuser/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
unbound    stopped 

I change the file name in this path, you can also remove it

mv /Users/myuser/Library/LaunchAgents/homebrew.mxcl.postgresql.plist /Users/myuser/Library/LaunchAgents/homebrew.mxcl.postgresql.plist_temp

and then reboot the os

sudo reboot

after booting I started the postgresql and it worked.

brew services start postgresql

Answer 23

就我而言，在 Ruby on Rails 项目中，我从tmp/pids文件夹中删除了一个 .pid 文件并重新启动系统。

Answer 24

Had the same issue. I checked that my database.yml file, (dev mode) host was pointing to 5433. I updated it to 5432 and it worked.

Answer 25

In my case PostgreSQL updates from version 13.4 to 14 in background, so it fixes by:

brew postgresql-upgrade-database

And after start or restart service postgresql :

brew services restart postgresql

PS: How you can understand what is the problem?

For first : see that 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 text error

Answer 26

Just in case someone needs this for windows , read on.

On windows hit the Windows button + R then enter services.msc and look for postgresql-x64-14 , Right click it and click start

Then go back to your PgAdmin4 for windows and then enter your master password if asked. From here, you should be able to proceed as usual with viewing of the db schemas.

Also, for Django, restart your server with CTR+C then python manage.py runserver (assuming you're working inside a virtual env)

Good luck

Answer 27

ps -ef|grep postgres

Then kill the process with PID

sudo kill -9 PID

Then start the postgresql

sudo service postgresql start