Common SSL issues on Python and how to fix it

• Python’s CERTIFICATE_VERIFY_FAILED errors happen when your system can’t chain the server’s certificate back to a trusted root.
• The safe fix is to update your system’s CA certificates — install certifi, or run Install Certificates.command on macOS.
• Disabling SSL verification works as a development-only workaround but should never ship to production.

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The error

[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate

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Recommended fix: refresh your CA bundle

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Update certifi (all OSes)

pip install --upgrade certifi

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Install Certificates (macOS only)

1. Open Spotlight (Cmd + Space).
2. Type Install Certificates.command and run it.

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Explicit certifi-aware context

import ssl
import certifi
from urllib.request import urlopen

url = "https://ethereum-mainnet.core.chainstack.com/AUTH_KEY"
context = ssl.create_default_context(cafile=certifi.where())
response = urlopen(url, context=context)

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Development-only workarounds

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Unverified ssl context

import ssl
import urllib.request

context = ssl._create_unverified_context()
urllib.request.urlopen(url, context=context)

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Override the default HTTPS context

import ssl

ssl._create_default_https_context = ssl._create_unverified_context

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requests with verify=False

import requests

requests.get(url, verify=False)

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See also

• Best practices for error handling in API requests
• Stack Overflow: CERTIFICATE_VERIFY_FAILED — unable to get local issuer certificate