urllib3 py.typed removed from dist package data (Fix)

The Fix

pip install urllib3==1.26.7

Based on closed urllib3/urllib3 issue #2729 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Open PR/Commit

@@ -1,4 +1,4 @@
@@ -1,4 +1,4 @@
-include README.rst CHANGES.rst LICENSE.txt dev-requirements.txt Makefile
+include README.rst CHANGES.rst LICENSE.txt dev-requirements.txt Makefile src/urllib3/py.typed
 recursive-include dummyserver *

fix.md

Option A — Upgrade to fixed release\npip install urllib3==1.26.7\nWhen NOT to use: This fix should not be used if the package does not require type checking.\n\n

Why This Fix Works in Production

Trigger: error: Skipping analyzing "urllib3": module is installed, but missing library stubs or py.typed marker
Mechanism: Included the py.typed file in the package to comply with PEP 561, allowing type checkers to recognize inline type annotations.
Why the fix works: Included the py.typed file in the package to comply with PEP 561, allowing type checkers to recognize inline type annotations. (first fixed release: 1.26.7).

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

Surfaces as: error: Skipping analyzing "urllib3": module is installed, but missing library stubs or py.typed marker

Proof / Evidence

GitHub issue: #2729
Fix PR: https://github.com/urllib3/urllib3/pull/2296
First fixed release: 1.26.7
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.75
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.75

Discussion

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

Jump to Sources Open on GitHub

“There might be a misunderstanding here due to how we do branching”

@sethmlarson · 2022-08-29 · confirmation · source

“I double checked and if you build a wheel from the main branch with python -m build the py.typed file is correctly included.”

@pquentin · 2022-08-29 · source

“@sethmlarson @pquentin thank you both, I was just checking versions distributed here: https://pypi.org/project/urllib3/#files, confusion on my part about branching strategy I think, appreciate your time…”

@symonk · 2022-08-29 · source

Failure Signature (Search String)

error: Skipping analyzing "urllib3": module is installed, but missing library stubs or py.typed marker

Error Message

Stack trace

error.txt

Error Message
-------------
error: Skipping analyzing "urllib3": module is installed, but missing library stubs or py.typed marker

What Broke

Mypy fails to analyze urllib3 due to missing type information, leading to type-checking issues.

Fix Options (Details)

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

pip install urllib3==1.26.7

When NOT to use: This fix should not be used if the package does not require type checking.

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/2296

First fixed release: 1.26.7

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

When NOT to Use This Fix

This fix should not be used if the package does not require type checking.
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
1.26.7	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.