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php – mysqli::mysqli(): (HY000/2002): Can't connect to local MySQL server through socket 'MySQL' (2)

Posted by: admin April 23, 2020 Leave a comment


I get this error when I try to connect to the mysql database using php mysqli class. Using following code:

$db = new MySQLi("localhost","kamil","*****");
if (mysqli_connect_errno())
    echo "An error occured. Please try again later.";

password is * for security.

I have created user kamil with all privileges on external ip address and localhost. When I run: select user,host from mysql.user it properly displays those two users.

I did some research and used this benchmark: https://stackoverflow.com/a/2183134/1839439 to see what it connects to. As it turns out it is only able to connect to and which is localhost, however when I supply localhost it throws out this error.

My question is why does it only allow me to connect to DB using localhost ip address and not the name or external ip. Do I need a different host if I want to be able to use mysql on website or if I can use

hosts file       localhost
::1             localhost ip6-localhost ip6-loopback
fe00::0         ip6-localnet
ff00::0         ip6-mcastprefix
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters       raspberrypi

Mysql user table results for this user:

| kamil            | |
| kamil            | localhost      |
How to&Answers:

When you use just “localhost” the MySQL client library tries to use a Unix domain socket for the connection instead of a TCP/IP connection. The error is telling you that the socket, called MySQL, cannot be used to make the connection, probably because it does not exist (error number 2).

From the MySQL Documentation:

On Unix, MySQL programs treat the host name localhost specially, in a
way that is likely different from what you expect compared to other
network-based programs. For connections to localhost, MySQL programs
attempt to connect to the local server by using a Unix socket file.
This occurs even if a –port or -P option is given to specify a port
number. To ensure that the client makes a TCP/IP connection to the
local server, use –host or -h to specify a host name value of, or the IP address or name of the local server. You can also specify the connection protocol explicitly, even for localhost, by
using the –protocol=TCP option.

There are a few ways to solve this problem.

  1. You can just use TCP/IP instead of the Unix socket. You would do this by using instead of localhost when you connect. The Unix socket might by faster and safer to use, though.
  2. You can change the socket in php.ini: open the MySQL configuration file my.cnf to find where MySQL creates the socket, and set PHP’s mysqli.default_socket to that path. On my system it’s /var/run/mysqld/mysqld.sock.
  3. Configure the socket directly in the PHP script when opening the connection. For example:

    $db = new MySQLi('localhost', 'kamil', '***', '', 0, 


If it’s a PHP issue, you could simply alter the configuration file php.ini wherever it’s located and update the settings for PORT/SOCKET-PATH etc to make it connect to the server.

In my case, I opened the file php.ini and did

mysql.default_socket = /var/run/mysqld/mysqld.sock
mysqli.default_socket = /var/run/mysqld/mysqld.sock

And it worked straight away. I have to admit, I took hint from the accepted answer by @Joni


Please check the following file


The line which bind the host name with ip is probably missing a line which bind them togather  localhost

If the given line is missing. Add the line in the file

Could you also check your MySQL database’s user table and tell us the host column value for the user which you are using. You should have user privilege for both the host “” and “localhost” and use % as it is a wild char for generic host name.


If ‘localhost’ doesn’t work but does. Make sure your local hosts file points to the correct location. (/etc/hosts for linux/mac, C:\Windows\System32\drivers\etc\hosts for windows).

Also, make sure your user is allowed to connect to whatever database you’re trying to select.