Python - SSL: CERTIFICATE_VERIFY_FAILED 에러

오랜만에 올리는 에러 포스트!

개요

python으로 외부 사이트를 긁어오는 작업 진행 중 아래와 같은 오류를 만났다.

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1348, in do_open
    h.request(req.get_method(), req.selector, req.data, headers,
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1286, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1332, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1281, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1041, in _send_output
    self.send(msg)
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 979, in send
    self.connect()
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1458, in connect
    self.sock = self._context.wrap_socket(self.sock,
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/ssl.py", line 517, in wrap_socket
    return self.sslsocket_class._create(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/ssl.py", line 1108, in _create
    self.do_handshake()
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/ssl.py", line 1379, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1006)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/kimchi/Desktop/my project/lambda_deployment_package/test.py", line 4, in <module>
    c_list = CurrencyConverter(url)
             ^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/currency_converter/currency_converter.py", line 144, in __init__
    self.load_file(currency_file)
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/currency_converter/currency_converter.py", line 149, in load_file
    content = urlopen(currency_file).read()
              ^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 216, in urlopen
    return opener.open(url, data, timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 519, in open
    response = self._open(req, data)
               ^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 536, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 496, in _call_chain
    result = func(*args)
             ^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1391, in https_open
    return self.do_open(http.client.HTTPSConnection, req,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1351, 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:1006)>

---

해결방법

찾아보니 이는 SSL 인증서 검증 실패로 인해 발생한 오류로 인증서를 업데이트해서 해결할 수 있었다.
운영체제별로 아래의 명령어를 사용해서 해결해보자

MacOS

/Applications/Python\ 3.11/Install\ Certificates.command

windows

C:\Python\Python3x\Install\Certificates.command

Ubuntu/Linux

sudo apt-get update
sudo apt-get install --reinstall ca-certificates

sudo update-ca-certificates

---

예시 검증 코드

SSL 업데이트가 정상적으로 이루어졌다면 아래 코드를 실행했을때 에러가 발생하지 않는다.

import ssl
import urllib.request

url = "https://example.com"
context = ssl.create_default_context()

try:
    response = urllib.request.urlopen(url, context=context)
    print(response.read())
except Exception as e:
    print(e)