Can't connect to local MySQL server through socket '/tmp/mysql.sock

Question

When I attempted to connect to a local MySQL server during my test suite, it fails with the error:

OperationalError: (2002, "Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)")

However, I'm able to at all times, connect to MySQL by running the command line mysql program. A ps aux | grep mysql shows the server is running, and stat /tmp/mysql.sock confirm that the socket exists. Further, if I open a debugger in except clause of that exception, I'm able to reliably connect with the exact same parameters.

This issue reproduces fairly reliably, however it doesn't appear to be 100%, because every once in a blue moon, my test suite does in fact run without hitting this error. When I attempted to run with sudo dtruss it did not reproduce.

All the client code is in Python, though I can't figure how that'd be relevant.

Switching to use host 127.0.0.1 produces the error:

DatabaseError: Can't connect to MySQL server on '127.0.0.1' (61)

Answer 1

sudo /usr/local/mysql/support-files/mysql.server start 

This worked for me. However, if this doesnt work then make sure that mysqld is running and try connecting.

Answer 2

For me the problem was I wasn't running MySQL Server. Run server first and then execute mysql.

$ mysql.server start
$ mysql -h localhost -u root -p

Answer 3

The relevant section of the MySQL manual is here. I'd start by going through the debugging steps listed there.

Also, remember that localhost and 127.0.0.1 are not the same thing in this context:

• If host is set to localhost, then a socket or pipe is used.
• If host is set to 127.0.0.1, then the client is forced to use TCP/IP.

So, for example, you can check if your database is listening for TCP connections vi netstat -nlp. It seems likely that it IS listening for TCP connections because you say that mysql -h 127.0.0.1 works just fine. To check if you can connect to your database via sockets, use mysql -h localhost.

If none of this helps, then you probably need to post more details about your MySQL config, exactly how you're instantiating the connection, etc.

Answer 4

I just changed the HOST from localhost to 127.0.0.1 and it works fine:

# settings.py of Django project
...

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'db_name',
        'USER': 'username',
        'PASSWORD': 'password',
        'HOST': '127.0.0.1',
        'PORT': '',
},
...

Answer 5

I've seen this happen at my shop when my devs have a stack manager like MAMP installed that comes preconfigured with MySQL installed in a non standard place.

at your terminal run

mysql_config --socket

that will give you your path to the sock file. take that path and use it in your DATABASES HOST paramater.

What you need to do is point your

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'test',
        'USER': 'test',
        'PASSWORD': 'test',
        'HOST': '/Applications/MAMP/tmp/mysql/mysql.sock',
        'PORT': '',
    },
}

NOTE

also run which mysql_config if you somehow have multiple instances of mysql server installed on the machine you may be connecting to the wrong one.

Answer 6

For me, the mysql server was not running. So, i started the mysql server through

mysql.server start

then

mysql_secure_installation

to secure the server and now I can visit the MySQL server through

mysql -u root -p

or

sudo mysql -u root -p

depending on your installation.

Answer 7

When, if you lose your daemon mysql in mac OSx but is present in other path for exemple in private/var do the following command

1)

ln -s /private/var/mysql/mysql.sock /tmp/mysql.sock

2) restart your connexion to mysql with :

mysql -u username -p -h host databasename

works also for mariadb

Answer 8

Run the below cmd in terminal

/usr/local/mysql/bin/mysqld_safe

Then restart the machine to take effect. It works!!

Answer 9

After attempting a few of these solutions and not having any success, this is what worked for me:

1. Restart system
2. mysql.server start
3. Success!

Answer 10

To those who upgraded from 5.7 to 8.0 via homebrew, this error is likely caused by the upgrade not being complete. In my case, mysql.server start got me the following error:

ERROR! The server quit without updating PID file

I then checked the log file via cat /usr/local/var/mysql/YOURS.err | tail -n 50, and found the following:

InnoDB: Upgrade after a crash is not supported.

If you are on the same boat, first install [email protected] via homebrew, stop the server, and then start the 8.0 system again.

brew install [email protected]

/usr/local/opt/[email protected]/bin/mysql.server start
/usr/local/opt/[email protected]/bin/mysql.server stop

Then,

mysql.server start

This would get your MySQL (8.0) working again.

Answer 11

I have two sneaky conjectures on this one

CONJECTURE #1

Look into the possibility of not being able to access the /tmp/mysql.sock file. When I setup MySQL databases, I normally let the socket file site in /var/lib/mysql. If you login to mysql as root@localhost, your OS session needs access to the /tmp folder. Make sure /tmp has the correct access rights in the OS. Also, make sure the sudo user can always read file in /tmp.

CONJECTURE #2

Accessing mysql via 127.0.0.1 can cause some confusion if you are not paying attention. How?

From the command line, if you connect to MySQL with 127.0.0.1, you may need to specify the TCP/IP protocol.

mysql -uroot -p -h127.0.0.1 --protocol=tcp

or try the DNS name

mysql -uroot -p -hDNSNAME

This will bypass logging in as root@localhost, but make sure you have root@'127.0.0.1' defined.

Next time you connect to MySQL, run this:

SELECT USER(),CURRENT_USER();

What does this give you?

• USER() reports how you attempted to authenticate in MySQL
• CURRENT_USER() reports how you were allowed to authenticate in MySQL

If these functions return with the same values, then you are connecting and authenticating as expected. If the values are different, you may need to create the corresponding user [email protected].

Answer 12

Check number of open files for the mysql process using lsof command.

Increase the open files limit and run again.

Answer 13

This may be one of following problems.

1. Incorrect mysql lock. solution: You have to find out the correct mysql socket by,

mysqladmin -p variables | grep socket

and then put it in your db connection code:

pymysql.connect(db='db', user='user', passwd='pwd', unix_socket="/tmp/mysql.sock")

/tmp/mysql.sock is the returned from grep

2.Incorrect mysql port solution: You have to find out the correct mysql port:

mysqladmin -p variables | grep port

and then in your code:

pymysql.connect(db='db', user='user', passwd='pwd', host='localhost', port=3306)

3306 is the port returned from the grep

I think first option will resolve your problem.

Answer 14

if you get an error like below :

django.db.utils.OperationalError: (2002, "Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)")

Then just find your mysqld.sock file location and add it to "HOST".

Like i am using xampp on linux so my mysqld.sock file is in another location. so it is not working for '/var/run/mysqld/mysqld.sock'

DATABASES = {

    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'asd',
        'USER' : 'root',
        'PASSWORD' : '',
        'HOST' : '/opt/lampp/var/mysql/mysql.sock',
        'PORT' : ''
    }
}

Answer 15

I think i saw this same behavior some time ago, but can't remember the details.
In our case, the problem was the moment the testrunner initialises database connections relative to first database interaction required, for instance, by import of a module in settings.py or some __init__.py. I'll try to digg up some more info, but this might already ring a bell for your case.

Answer 16

Make sure your /etc/hosts has 127.0.0.1 localhost in it and it should work fine

Answer 17

Had this same problem. Turned out mysqld had stopped running (I'm on Mac OSX). I restarted it and the error went away.

I figured out that mysqld was not running largely because of this link: http://dev.mysql.com/doc/refman/5.6/en/can-not-connect-to-server.html

Notice the first tip!

Answer 18

I had to kill off all instances of mysql by first finding all the process IDs:

ps aux | grep mysql

And then killing them off:

kill -9 {pid}

Then:

mysql.server start

Worked for me.

Answer 19

Check that your mysql has not reached maximum connections, or is not in some sort of booting loop as happens quite often if the settings are incorrect in my.cnf.

Use ps aux | grep mysql to check if the PID is changing.

Answer 20

Looked around online too long not to contribute. After trying to type in the mysql prompt from the command line, I was continuing to receive this message:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

This was due to the fact that my local mysql server was no longer running. In order to restart the server, I navigated to

shell> cd /user/local/bin

where my mysql.server was located. From here, simply type:

shell> mysql.server start

This will relaunch the local mysql server.

From there you can reset the root password if need be..

mysql> UPDATE mysql.user SET Password=PASSWORD('MyNewPass')
->                   WHERE User='root';
mysql> FLUSH PRIVILEGES;

Answer 21

This worked for me :

mysql.server start
mysql -u root -p

Answer 22

The socket is located in /tmp. On Unix system, due to modes & ownerships on /tmp, this could cause some problem. But, as long as you tell us that you CAN use your mysql connexion normally, I guess it is not a problem on your system. A primal check should be to relocate mysql.sock in a more neutral directory.

The fact that the problem occurs "randomly" (or not every time) let me think that it could be a server problem.

• Is your /tmp located on a standard disk, or on an exotic mount (like in the RAM) ?

• Is your /tmp empty ?

• Does iotopshow you something wrong when you encounter the problem ?

Answer 23

If it's socket related read this file

/etc/mysql/my.cnf

and see what is the standard socket location. It's a line like:

socket = /var/run/mysqld/mysqld.sock

now create an alias for your shell like:

alias mysql="mysql --socket=/var/run/mysqld/mysqld.sock"

This way you don't need root privileges.

Answer 24

# shell script ,ignore the first 
$ $(dirname `which mysql`)\/mysql.server start

May be helpful.

Answer 25

I had faced similar problem recently. Went through many answers. I got it working by following steps.

1. change the socket path in /etc/my.cnf (as i was repeatedly getting error with /tmp/mysql.sock ) reference to change the socket path
2. run mysqld_safe to restart the server as it is the recommended way to restart in case of errors. reference to mysqld_safe

Answer 26

If you installed through Homebrew, try to run

brew services start mysql

Answer 27

Configure your DB connection in the 'Manage DB Connections dialog. Select 'Standard (TCP/IP)' as connection method.

See this page for more details http://dev.mysql.com/doc/workbench/en/wb-manage-db-connections.html

According to this other page a socket file is used even if you specify localhost.

A Unix socket file is used if you do not specify a host name or if you specify the special host name localhost.

It also shows how to check on your server by running these commands:

If a mysqld process is running, you can check it by trying the following commands. The port number or Unix socket file name might be different in your setup. host_ip represents the IP address of the machine where the server is running.

shell> mysqladmin version 
shell> mysqladmin variables 
shell> mysqladmin -h `hostname` version variables 
shell> mysqladmin -h `hostname` --port=3306 version 
shell> mysqladmin -h host_ip version 
shell> mysqladmin --protocol=SOCKET --socket=/tmp/mysql.sock version

Answer 28

in ubuntu14.04 you can do this to slove this problem.

zack@zack:~/pycodes/python-scraping/chapter5$ **mysqladmin -p variables|grep socket**
Enter password: 
| socket                                            | ***/var/run/mysqld/mysqld.sock***                                                                                            |
zack@zack:~/pycodes/python-scraping/chapter5$***ln -s  /var/run/mysqld/mysqld.sock /tmp/mysql.sock***
zack@zack:~/pycodes/python-scraping/chapter5$ ll /tmp/mysql.sock 
lrwxrwxrwx 1 zack zack 27 11月 29 13:08 /tmp/mysql.sock -> /var/run/mysqld/mysqld.sock=

Answer 29

For me, I'm sure mysqld is started, and command line mysql can work properly. But the httpd server show the issue(can't connect to mysql through socket).

I started the service with mysqld_safe&.

finally, I found when I start the mysqld service with service mysqld start, there are issues(selinux permission issue), and when I fix the selinux issue, and start the mysqld with "service mysqld start", the httpd connection issue disappear. But when I start the mysqld with mysqld_safe&, mysqld can be worked. (mysql client can work properly). But there are still issue when connect with httpd.

Answer 30

Simply try to run mysqld.

This was what was not working for me on mac. If it doesn't work try go to /usr/local/var/mysql/<your_name>.err to see detailed error logs.