urllib3 Add BaseHTTPResponse to urllib3.__all_

The Fix

pip install urllib3==2.0.4

Based on closed urllib3/urllib3 issue #3078 · PR/commit linked

Production note: This usually shows up under retries/timeouts. Treat it as a side-effect risk until you can verify behavior with a canary + real traffic.

Open PR/Commit

@@ -0,0 +1 @@
@@ -0,0 +1 @@
+Added ``BaseHTTPResponse`` to ``__all__`` in ``__init__.py``
diff --git a/src/urllib3/__init__.py b/src/urllib3/__init__.py
index 7ddfad2006..32c1f0025f 100644

fix.md

Option A — Upgrade to fixed release\npip install urllib3==2.0.4\nWhen NOT to use: This fix is not applicable if you do not require BaseHTTPResponse for type hinting.\n\n

Why This Fix Works in Production

Trigger: Is it something you currently cannot do?
Mechanism: BaseHTTPResponse was not included in the __all__ dunder, preventing type hinting
Why the fix works: Added BaseHTTPResponse to __all__ for type hinting purposes. (first fixed release: 2.0.4).

Production impact:

If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.

Why This Breaks in Prod

Shows up under Python 3.9 in real deployments (not just unit tests).
BaseHTTPResponse was not included in the __all__ dunder, preventing type hinting
Production symptom (often without a traceback): Is it something you currently cannot do?

Proof / Evidence

GitHub issue: #3078
Fix PR: https://github.com/urllib3/urllib3/pull/3080
First fixed release: 2.0.4
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.77

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“Sounds like a good idea, thanks for suggesting it. If you're interested you can make this change yourself or we can wait for someone else…”

@sethmlarson · 2023-06-27 · source

“Hey Team, From today morning, I am facing this issue - cannot import name 'BaseHTTPResponse' from 'urllib3' (/databricks/python/lib/python3.9/site-packages/urllib3/__init__.py) Could you suggest, what could be the…”

@parthpatel231 · 2023-08-11 · source

“@parthpatel231 See this: https://github.com/databricks/databricks-sql-python/issues/194”

@tiagofilipenunes · 2023-08-14 · source

Failure Signature (Search String)

Is it something you currently cannot do?
* I currently cannot due this do to BaseHTTPResponse not being defined within the __all__ dunder.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Is it something you currently cannot do?
* I currently cannot due this do to BaseHTTPResponse not being defined within the __all__ dunder.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Is it something you currently cannot do?
* I currently cannot due this do to BaseHTTPResponse not being defined within the __all__ dunder.

Environment

Python: 3.9

What Broke

Users cannot import BaseHTTPResponse, leading to type hinting issues in their code.

Why It Broke

BaseHTTPResponse was not included in the __all__ dunder, preventing type hinting

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install urllib3==2.0.4

When NOT to use: This fix is not applicable if you do not require BaseHTTPResponse for type hinting.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Option D — Guard side-effects with OnceOnly Guardrail for side-effects

Mitigate duplicate external side-effects under retries/timeouts/agent loops by gating the operation before calling external systems.

Place OnceOnly between your code/agent and real side-effects (Stripe, emails, CRM, APIs).
Use a stable key per side-effect (e.g., customer_id + action + idempotency_key).
Fail-safe: configure fail-open vs fail-closed based on blast radius and spend risk.

Show example snippet (optional)

onceonly.py

from onceonly import OnceOnly
import os

once = OnceOnly(api_key=os.environ["ONCEONLY_API_KEY"], fail_open=True)

# Stable idempotency key per real side-effect.
# Use a request id / job id / webhook delivery id / Stripe event id, etc.
event_id = "evt_..."  # replace
key = f"stripe:webhook:{event_id}"

res = once.check_lock(key=key, ttl=3600)
if res.duplicate:
    return {"status": "already_processed"}

# Safe to execute the side-effect exactly once.
handle_event(event_id)

See OnceOnly SDK

When NOT to use: Do not use this to hide logic bugs or data corruption. Use it to block duplicate external side-effects and enforce tool permissions/spend caps.

Fix reference: https://github.com/urllib3/urllib3/pull/3080

First fixed release: 2.0.4

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

This fix is not applicable if you do not require BaseHTTPResponse for type hinting.
Do not use this to hide logic bugs or data corruption. Use it to block duplicate external side-effects and enforce tool permissions/spend caps.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
Upgrade behind a canary and run integration tests against the canary before 100% rollout.

Version Compatibility Table

Version	Status
2.0.4	Fixed

Related Issues

No related fixes found.

Cluster: urllib3:configuration-error urllib3 hub urllib3 best practices All hubs All clusters

Related clusters: Data consistency SSL handshake Other

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.

urllib3 Add BaseHTTPResponse to urllib3.__all__ (Fix)