SSL: CERTIFICATE_VERIFY_FAILED in Python (pip, requests, urllib)

macOS — python.org install (most common cause)

1. # Open Finder > Applications > Python 3.x folder
2. # Double-click: Install Certificates.command
3. pip install --upgrade certifi

All platforms — trusted hosts workaround for pip

1. pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org [package-name]

All platforms — permanent fix via certifi upgrade

1. pip install --upgrade certifi
2. python -c "import certifi; print(certifi.where())"

• If Error occurs on macOS with Python from python.org → Run 'Install Certificates.command' from /Applications/Python 3.x/ then retry
• If Error occurs on a corporate network → Get the corporate CA certificate from IT, then: pip install --cert /path/to/corp-ca.crt certifi
• If Error only in pip but browser HTTPS works → Browser uses system certificates; Python uses certifi. Run: pip install --upgrade certifi

• Virtual environments: certifi must be installed inside the active venv — activate it first, then run pip install --upgrade certifi
• Conda environments: use 'conda update certifi' instead of pip to keep certificates in sync with conda's CA bundle
• Self-signed certs in development: set REQUESTS_CA_BUNDLE=/path/to/your-cert.pem as an environment variable so requests always uses it

# Recommended permanent fix: upgrade certifi
pip install --upgrade certifi

# pip workaround (when certifi upgrade is not possible)
pip install --trusted-host pypi.org \
  --trusted-host files.pythonhosted.org \
  [package-name]

# requests library: use explicit CA bundle
import requests
requests.get("https://example.com", verify="/path/to/ca-bundle.crt")

# Verify fix
python -c "import urllib.request; urllib.request.urlopen('https://pypi.org')" && echo "SSL OK"