Failed to install Poetry on macOS Catalina for Python3

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: macOS 10.15.7
• Poetry version: 0.14
• Link of a Gist with the contents of your pyproject.toml file:

Issue

I’m trying to install Poetry using the download script get-poetry.py with the official Python 3.9.1 downloaded from python.org. But failed with the following errors.

$ python3 get-poetry.py 
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 1342, in do_open
    h.request(req.get_method(), req.selector, req.data, headers,
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/client.py", line 1255, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/client.py", line 1301, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/client.py", line 1250, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/client.py", line 1010, in _send_output
    self.send(msg)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/client.py", line 950, in send
    self.connect()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/http/client.py", line 1424, in connect
    self.sock = self._context.wrap_socket(self.sock,
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ssl.py", line 500, in wrap_socket
    return self.sslsocket_class._create(
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ssl.py", line 1040, in _create
    self.do_handshake()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ssl.py", line 1309, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1123)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/me/Desktop/_dev/get-poetry.py", line 1086, in <module>
    sys.exit(main())
  File "/Users/me/Desktop/_dev/get-poetry.py", line 1060, in main
    urlopen(Installer.REPOSITORY_URL)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 214, in urlopen
    return opener.open(url, data, timeout)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 517, in open
    response = self._open(req, data)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 534, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 494, in _call_chain
    result = func(*args)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 1385, in https_open
    return self.do_open(http.client.HTTPSConnection, req,
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/urllib/request.py", line 1345, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1123)>

Using the system builtin Python2.7, I got no such errors. But since py27 is deprecated for Poetry. I got no choice but to use Python3.

If I’m the only one with this problem, then it must be my own setup, but what am I missing?

[pemistahl]

Navigating to Application/Python 3.9 folder, you will see the command file shipped with Python: Install Certificates.command. Run that command

I had the same problem like the author. Executing the command above solved it for me and I could install poetry using Python 3.9.

[kottn]

@sanders41 Thanks a lot. I solved. The problem was Proxy settings as you said.