psql: could not connect to server: No such file or directory (Mac OS X)

Question

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.

As a sanity check, make sure you have PG running on your machine — Jbur43, Dec 18 '15 at 19:10
When you leave the answer please try to explain WHY this is happening, or how the Postgres system work so we're not all just trying random stuff. — Nick Res, Jun 04 '18 at 13:48
`brew reinstall postgresql` https://stackoverflow.com/a/39781473/6086226 worked for me — Derk Jan Speelman, May 02 '19 at 07:12

score 456 · Accepted Answer · edited May 18 '17 at 14:26

456

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.

edited May 18 '17 at 14:26

Flip

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answered Nov 26 '12 at 21:09

FireDragon

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hopefully this answer ends up helping someone else out, and thank you to the person that upvoted it. despite the moderator who marked this question as a duplicate it is unique and useful. thanks stack overflow for the awesome site and the experts on here for sharing! – FireDragon Nov 28 '12 at 03:59
2

Just FWIW, deleting postmaster.pid is dangerous, you've got to be *really* sure there are no `postgres` processes running before you do it. – Craig Ringer Jun 07 '13 at 00:19
25

Great answer. Thanks for posting your entire process rather than just the potentially destructive command! – dojosto Apr 13 '14 at 22:29
3

Agreed. The answer about postmaster.pid is good, but each step of the process of figuring out if/where postgres is running, is *invaluable*. Thank you! – Clinton Jun 18 '14 at 15:52
14

My postgres log on macos was at `/usr/local/var/log/postgres.log`. – ryantuck Jun 13 '18 at 15:55
1

Before deleting anything, try `brew reinstall postgresql`. That fixed it for me. – Derk Jan Speelman May 02 '19 at 07:13
Man, You are a hero – Milind Chaudhary Nov 02 '20 at 05:13

score 208 · Answer 2 · edited May 16 '21 at 14:24

208

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)

edited May 16 '21 at 14:24

Gianfranco P.

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answered Oct 27 '17 at 09:30

ypicard

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Worked for me, yet I did not have to remove an actual database and didn't have a folder in Application Support. I think the point was that some brew elements had broken symlinks while installing postgres. Fixing them and installing postgres again solved the issue. Thanks! – Kulbi Jan 15 '19 at 20:18
5

Neither this nor top answer worked for me, until I also ran `brew postgresql-upgrade-database` – ErikAGriffin Dec 02 '19 at 21:27
These worked for me, except I didn't have to delete the old data. – Amal Antony Apr 26 '20 at 12:58
To confirm: this deletes all your databases, correct? I was able to get by with just a `brew reinstall postgres`, confirming that the latest Homebrew Postgres major version number was the same as my current (broken) one. – Jacob Ford Apr 28 '20 at 04:12
@JacobFord are you saying that `brew reinstall postgresql` won't wipe your dbs? – bplittle Feb 05 '21 at 20:00
Thanks! it is Old but gold! – iamkdblue Feb 20 '21 at 06:13

score 95 · Answer 3 · edited Oct 31 '18 at 00:46

95

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

edited Oct 31 '18 at 00:46

Boris

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answered Jun 15 '15 at 09:12

Jagdish Barabari

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score 46 · Answer 4 · edited Apr 17 '19 at 19:39

46

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

edited Apr 17 '19 at 19:39

Fred Willmore

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answered Jul 31 '18 at 10:52

Crazy Barney

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This worked for me on going from 11 to 12 on Catalina – nzajt Nov 25 '19 at 23:07
1

Worked for me as well – emptywalls Mar 06 '20 at 03:14

score 26 · Answer 5 · answered Sep 17 '19 at 12:16

26

Here is my way:

launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
rm /usr/local/var/postgres/postmaster.pid
launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

answered Sep 17 '19 at 12:16

smartworld-dm

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This worked for me when no other stopping and starting/restarting/reinstalling of Postgres using homebrew was done. Thanks @smartworld-dm – Bradley Nov 20 '19 at 13:41
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This is the soultion I always come back to. I might add a alias that when I run `fix-my-postgresql` it will execute this :) – Tomas K Feb 11 '20 at 12:57
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Any idea why I have to do this every time I reboot my PC? – stephano Apr 12 '20 at 22:00
2

Similar but different :) ... brew services stop postgresql; rm /usr/local/var/postgres/postmaster.pid; brew services start postgresql – Roger Heathcote Aug 19 '20 at 18:11

score 11 · Answer 6 · answered Dec 05 '17 at 01:00

11

if your postmaster.pid is gone and you can't restart or anything, do this:

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

as explained here initially

answered Dec 05 '17 at 01:00

Antoine

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score 9 · Answer 7 · answered Nov 13 '20 at 09:53

9

Another class of reasons why this can happen is due to Postgres version updates.

You can confirm this is a problem by looking at the postgres logs:

tail -n 10000 /usr/local/var/log/postgres.log

and seeing entries like:

DETAIL:  The data directory was initialized by PostgreSQL version 12, which is not compatible with this version 13.0.

In this case (assuming you are on Mac and using brew), just run:

brew postgresql-upgrade-database

(Oddly, it failed on run 1 and worked on run 2, so try it twice before giving up)

answered Nov 13 '20 at 09:53

Jack Kinsella

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This worked for me and I had to run it twice as well - first time it failed with the original error: ```connection to database failed: could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/usr/local/var/log/.s.PGSQL.50432"? ``` but running it a second time worked ¯\＿(ツ)＿/¯ – ea0723 Mar 25 '21 at 23:42

crazzyaka · Answer 8 · 2014-02-01T21:38:54.790

Hello world :)
The best but strange way for me was to do next things.

1) Download postgres93.app or other version. Add this app into /Applications/ folder.

2) Add a row (command) into the file .bash_profile (which is in my home directory):

export PATH=/Applications/Postgres93.app/Contents/MacOS/bin/:$PATH

It's a PATH to psql from Postgres93.app. The row (command) runs every time console is started.

3) Launch Postgres93.app from /Applications/ folder. It starts a local server (port is "5432" and host is "localhost").

4) After all of this manipulations I was glad to run $ createuser -SRDP user_name and other commands and to see that it worked! Postgres93.app can be made to run every time your system starts.

5) Also if you wanna see your databases graphically you should install PG Commander.app. It's good way to see your postgres DB as pretty data-tables

Of, course, it's helpful only for local server. I will be glad if this instructions help others who has faced with this problem.

The key here is adding Postgres to your path (step 2). That helped me. If you installed Postgres using Homebrew, you can add it to your path by adding the following line to your .bash_profile: `export PATH='/usr/local/Cellar/postgresql/9.4.1/bin/':$PATH` – Keep in mind your version number may be different. — Tina, Mar 14 '15 at 04:19

score 8 · Answer 9 · answered May 08 '17 at 04:47

For me, the solution was simply restart my computer. I first tried restarting with Brew services and when that didn't work, restarting seemed like the next best option to try before looking into some of the more involved solutions. Everything worked as it should after.

score 7 · Answer 10 · edited May 23 '17 at 12:34

This problema has many sources, and thus many answers. I've experienced each one of them.

1) If you have a crash of some sort, removing the /usr/local/var/postgres/postmaster.pid file is probably required as postgres may not have handled it properly. But ensure that no process is running.

2) Craig Ringer has pointed out in other posts that Apple's bundling of postgreSQL leads to pg gem installation issues Setting the PATH environment variable is a solution.

3) Another solution, is to uninstall and reinstall the gem. A brew update may be necessary as well.

If you stumble upon this post, if you can pinpoint one of the sources, you'll save time...

I'm glad I posted this. Another crash & the answer can be retreived rather quickly... — Jerome, Mar 28 '14 at 14:58

score 7 · Answer 11 · answered Jan 27 '21 at 04:09

7

The following commands helped me out. The issue was with the PostgreSQL data version. Once upgraded, it started working fine for me.

brew upgrade postgresql
brew postgresql-upgrade-database
brew services restart postgresql

answered Jan 27 '21 at 04:09

Satendra Rawat

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Surprised !!! I just install postgresql on my MAC OS than on connect, connection fail. postgresql not running in background when I start as service, but after these commands. All works perfectly. – Tejas Tank Mar 29 '21 at 06:48
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Glad it helped you @TejasTank – Satendra Rawat Apr 28 '21 at 06:49

score 5 · Answer 12 · answered May 13 '15 at 10:05

5

I was facing a similar issue here I solved this issue as below.

Actually the postgres process is dead, to see the status of postgres run the following command

sudo /etc/init.d/postgres status

It will says the process is dead`just start the process

sudo /etc/init.d/postgres start

answered May 13 '15 at 10:05

Jagdish Barabari

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Thankyou for the answer, your answer helped me solve the same issue with some modifications: sudo /etc/init.d/postgresql start – Pravitha V Feb 09 '17 at 11:15

score 4 · Answer 13 · answered Oct 20 '17 at 15:45

4

This happened to me after my Mac (High Sierra) froze and I had to manually restart it (press and hold the power button). All I had to do to fix it was do a clean restart.

answered Oct 20 '17 at 15:45

skwidbreth

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score 3 · Answer 14 · answered Jul 22 '15 at 18:00

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My problem ended up being that I was using Gas Mask (a hosts file manager for Mac), and I didn't have an entry for localhost in the hosts file I was using.

I added:

127.0.0.1 localhost

And that resolved my problem.

answered Jul 22 '15 at 18:00

jawns317

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score 3 · Answer 15 · answered Jun 04 '18 at 15:24

I'm not entirely sure why, but my Postgres installation got a little bit screwed and some files were deleted resulting in the error OP is showing.

Despite the fact that I am able to run commands like brew service retart postgres and see the proper messages, this error persisted.

I went through the postgres documentation and found that my file /usr/local/var/postgres was totally empty. So I ran the following:

initdb /usr/local/var/postgres

It seems some configurations took place with that command.

Then it asked me to run this:

postgres -D /usr/local/var/postgres

And that told me a postmaster.pid file already exists.

I just needed to know if brew would be able to pick up the configs I just ran, so I tested it out.

ls /usr/local/var/postgres

That showed me a postmaster.pid file. I then did brew services stop postgresql, and the postmaster.pid file disappeared. Then I did brew services start postgresql, and VIOLA, the file reappeared.

Then I went ahead and ran my app, which did in fact find the server, however my databases seem to be gone.

Although I know that they may not be gone at all - the new initialization I did may have created a new data_area, and the old one isn't being pointed to. I'd have to look at where that's at and point it back over or just create my databases again.

Hope this helps! Reading the postgres docs helped me a lot. I hate reading answers that are like "Paste this in it works!" because I don't know what the hell is happening and why.

score 3 · Answer 16 · answered Dec 27 '18 at 11:13

I had the same issue. Most of the times, the problem is the fact that there's a leftover file

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

which works for most people, but my case was different - I tried googling this issue for last 3 hours, uninstalled postresql on OSX through brew, purged the database, nothing worked.

Finally, I noticed that I had an issue with brew that whenever I tried to install anything, it popped:

Error: Permission denied @ rb_sysopen - /private/tmp/github_api_....

or something like it at the end of an install.

I simply did sudo chmod -R 777 /private/tmp and it finally works!

I'm writing this down because this might be a solution for someone else

score 3 · Answer 17 · answered Oct 05 '20 at 07:00

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

what worked for me -

remove postmaster.pid -- rm /usr/local/var/postgresql@9.6/postmaster.pid

restart postgres -- brew services restart postgresql@9.6

If postmaster.pid doesn't exist or the above process doesn't work then run --

sudo chmod 700 /usr/local/var/postgresql@9.6

score 2 · Answer 18 · answered Jan 26 '18 at 16:54

The causes of this error are many so first locate your log file and check it for clues. It might be at /usr/local/var/log/postgres.log or /usr/local/var/postgres/server.log or possibly elsewhere. If you installed with Homebrew you can find the location in ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist.

score 1 · Answer 19 · answered Jun 18 '19 at 10:06

1

Go to /var/log/ and run cat postgres.log Here you will find the reason for the failure of postgres. If it is a smart shut down then probably your icu4c version (C++ library for Unicode) is not proper which is linked with postgres. So run the following commands.

brew upgrade brew cleanup This should work ;)

answered Jun 18 '19 at 10:06

Shishir

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May have to run `brew style` afterwards if `brew cleanup` breaks Homebrew. – olliezhu Jan 15 '20 at 21:33

score 1 · Answer 20 · answered Apr 18 '21 at 08:17

I had the same issue and it was due to an incompatible version after upgrading from version 11 to 13.2

Checking error log at:

/usr/local/var/log/postgres.log

Showed me:

DETAIL:  The data directory was initialized by PostgreSQL version 11, which is not compatible with this version 13.2.

To fix I ran:

brew postgresql-upgrade-database

And then started postresql with brew:

brew services start postgresql

score 0 · Answer 21 · answered Jul 18 '14 at 20:20

0

I've had to look up this post several times to solve this issue. There's another fix, which will also applies to similar issues with other running programs.

I just discovered you can use the following two commands.

$top

This will show all the currently running actions with their pid numbers. When you find postgres and the associated pid

$kill pid_number

answered Jul 18 '14 at 20:20

cohart

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Similar to `ps aux | grep \[p\]ostgres | awk '{ print $2 }'` to return the pid, or `kill $(ps aux | grep \[p\]ostgres | awk '{ print $2 }')` (on zsh `[]` must be escaped as `\[\]`, but not on bash) – anothermh Sep 02 '20 at 18:08

score 0 · Answer 22 · answered Mar 02 '15 at 05:42

I just got the same issue as I have put my machine(ubuntu) for update and got below error:

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"?

After completing the updating process when I restart my system error gone. And its work like charm as before.. I guess this was happened as pg was updating and another process started.

score 0 · Answer 23 · answered May 01 '16 at 07:08

SUPER NEWBIE ALERT: I'm just learning web development and the particular tutorial I was following mentioned I have to install Postgres but didn't actually mention I have to run it as well... Once I opened the Postgres application everything was fine and dandy.

score 0 · Answer 24 · answered May 11 '16 at 17:20

0

@Jagdish Barabari's answer gave me the clue I needed to resolve this. Turns out there were two versions of postgresql installed while only one was running. Purging all postgresql files and reinstalling the latest version resolved this issue for me.

answered May 11 '16 at 17:20

5280Angel

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score 0 · Answer 25 · answered Apr 04 '19 at 16:19

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I removed /usr/lib from the LD_LIBRARY_PATH and it worked. I was working in dockerfile postgres:alpine.

answered Apr 04 '19 at 16:19

ddtraveller

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psql: could not connect to server: No such file or directory (Mac OS X)

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