When I try to connect to MySQL with mysql-connector-python, I cannot connect with the error "SSL connection error: SSL_CTX_set_tmp_dh failed"

Introduction

When I try to connect to a MySQL server started from a Docker image using Python's "mysql-connector-python" library, I get a "** SSL connection error: SSL_CTX_set_tmp_dh failed **" error and cannot connect to MySQL. Has occurred.

test.py

import mysql.connector

conn = mysql.connector.connect(
    host='127.0.0.1',
    port='3306',
    user='user',
    password='password', 
    database='sample_db'
)
cursor = conn.cursor()

↓ After execution

Error message

Traceback (most recent call last):
  File "/Users/user1/opt/anaconda3/lib/python3.7/site-packages/mysql/connector/connection_cext.py", line 200, in _open_connection
    self._cmysql.connect(**cnx_kwargs)
_mysql_connector.MySQLInterfaceError: SSL connection error: SSL_CTX_set_tmp_dh failed

# //abridgement

I will leave it as a memorandum because it is ready to connect once.

Execution environment

** ■ Client **

• macOS Catalina 10.15.2 --Use the following packages included in Anaconda3

$ conda list --show-channel-urls
mysql-connector-c         6.1.11               hccea1a4_0
mysql-connector-python    8.0.18           py37h3febbb0_1
openssl                   1.1.1d               h1de35cc_3
python                    3.7.4                h359304d_1

** ■ MySQL server ** --MySQL 5.7 (default setting)

Countermeasures

I specified use_pure = True as an argument when creating a DB connection, and changed the module to be used to the genuine Python version instead of the default C extended version, and now I can connect.

7.1 Connector/Python Connection Arguments

test.py

import mysql.connector

conn = mysql.connector.connect(
    host='127.0.0.1',
    port='3306',
    user='user',
    password='password',
    database='sample_db',
    use_pure=True  #← Add
)
cursor = conn.cursor()

As far as I can see, is this error a compatibility issue between mysql-connector-python and openssl? It seems that it is caused by. I haven't tried it in my environment, but according to the following issue, there is a comment that downgrading the openssl version to 1.0.2 made it possible to connect.

-MySQLdb and mysql.connector are incompatible with openssl 1.1.1a # 10646

In addition, it seems that the performance will be improved by using the C implementation version compared to the genuine Python, so be careful when handling a large amount of data.

-Chapter 8 The Connector / Python C Extension -SSL Error when connecting on Linux / Mac using Openssl 1.1.1 # 22n