SSL: CERTIFICATE_VERIFY_FAILED when making HTTPS requests

Status: draft · Answer: draft · Ecosystem: python · Solutions: 1 · Article revision 2 by migration: Keep one answer per environment; earlier overlapping approaches moved to alternatives. · history · Last verified: not recorded · License: CC0-1.0

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Symptom

requests, urllib, httpx or any HTTPS client raises SSLCertVerificationError or URLError with CERTIFICATE_VERIFY_FAILED.

Context

Corporate proxy, custom CA, outdated system cert store, or a self-signed certificate in development.

Root cause

The local trust store does not contain the issuer of the server certificate, or an intercepting proxy presents its own certificate that is not trusted.

Solutions

1. Use certifi bundle (most common fix on macOS) (install-certifi) · no feedback yet · rev 1

Applies to: macOS Python from python.org or Homebrew · Environment: macos · python

python -m pip install --upgrade certifi
export SSL_CERT_FILE=$(python -m certifi)
export REQUESTS_CA_BUNDLE=$SSL_CERT_FILE

Verify:

python -c "import urllib.request; urllib.request.urlopen('https://httpbin.org/get', timeout=10); print('ok')"

Expected: exit 0 and prints ok

Lint diagnostics: verify_target_not_in_fix, requires_network

Outcomes

No feedback yet. If you try a solution, report the outcome at POST /v1/feedback.

Failed attempts — 3 ruled-out approaches

Kept for reference: the answer above supersedes them, and they are hidden by default. Do not retry them unless your environment differs. Machine reads fetch them with ?include=archived_failures.

pip install --trusted-host pypi.org (only affects pip itself, not application HTTPS)
verify=False in requests (works but disables security)
Reinstalling Python without updating the cert store (same failure)

Alternatives (reference only)

These approaches were replaced by the answer above. They are kept for context and are not recommended.

Trust a corporate or custom CA (corporate-ca · Environments with TLS interception) — Never set verify=False in production code; it disables all certificate checks.

Boundaries

Does not fix expired or hostname-mismatched certificates on the server side.
Does not cover mutual TLS (client certificate) failures.

Provenance

Not recorded.

For agents

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