Is the server running on host “localhost” (::1) an

问题:

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?

回答1:

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/)

回答2:

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.

回答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

回答4:

It might be as simple as the postgresql service is down. Try running:

sudo service postgresql start

which fixed the issue for me.

回答5:

This worked in my case:

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

回答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

回答7:

This can be as pid file created for postgress have not been deleted due to unexpected shutdown. So 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

   rm postmaster.pid

3. Restart postgress. On Mac,

   brew services restart postgresql

回答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

回答9:

If you want to restart Postgresql on Linux, then you have to use the following command.

/etc/init.d/postgresql restart

回答10:

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

回答11:

I often encounter this problem on windows,the way I solved the problem is Service - Click PostgreSQL Database Server 8.3 - Click the second tab "log in" - choose the first line "the local system account".

回答12:

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!

回答13:

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.