The Fix
Upgrade to version 0.13.0 or later.
Based on closed encode/httpx issue #829 · PR/commit linked
@@ -4,6 +4,33 @@ All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+## 0.12.0 (March 5th, 2020)
+
+The 0.12 release tightens up the API expectations for `httpx` by switching to private module names to enforce better clarity around public API.
fix.md
Option A — Upgrade to fixed release\nUpgrade to version 0.13.0 or later.\nWhen NOT to use: Do not use this fix if you rely on the previous public API structure.\n\n
Why This Fix Works in Production
- Trigger: * Tighter management of connection pool state changes. Resolves #514, #283. (I'll also take a look at #282 at some point.)
- Mechanism: The 0.12 release tightens up the API expectations for httpx by switching to private module names to enforce better clarity around public API.
- Why the fix works: The 0.12 release tightens up the API expectations for httpx by switching to private module names to enforce better clarity around public API. (first fixed release: 0.13.0).
Why This Breaks in Prod
- Production symptom (often without a traceback): * Tighter management of connection pool state changes. Resolves #514, #283. (I'll also take a look at #282 at some point.)
Proof / Evidence
- GitHub issue: #829
- Fix PR: https://github.com/encode/httpx/pull/849
- First fixed release: 0.13.0
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.64
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“@tomchristie Looks like all PRs that ought to get in for 0.12 got merged”
“Ideally I'd like us to have #836 and then #23 (docs PRs) for the next release as well…”
“I could gladly help, if that’s desirable! I’m using httpx a lot in the place I work”
“Shold we consider resolving #302 part of the roadmap to 1.0?”
Failure Signature (Search String)
- * Tighter management of connection pool state changes. Resolves #514, #283. (I'll also take a look at #282 at some point.)
- We'd also need to drop UDS support if we want to get `httpcore` in. I should have pushed back harded on it in the first place - as nice as it is to have features++ it doesn't
Copy-friendly signature
signature.txt
Failure Signature
-----------------
* Tighter management of connection pool state changes. Resolves #514, #283. (I'll also take a look at #282 at some point.)
We'd also need to drop UDS support if we want to get `httpcore` in. I should have pushed back harded on it in the first place - as nice as it is to have features++ it doesn't really make the "feature set we need to focus on for 1.0".
Error Message
Signature-only (no traceback captured)
error.txt
Error Message
-------------
* Tighter management of connection pool state changes. Resolves #514, #283. (I'll also take a look at #282 at some point.)
We'd also need to drop UDS support if we want to get `httpcore` in. I should have pushed back harded on it in the first place - as nice as it is to have features++ it doesn't really make the "feature set we need to focus on for 1.0".
What Broke
Potential confusion and misuse of internal APIs leading to unexpected behavior.
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
Upgrade to version 0.13.0 or later.
When NOT to use: Do not use this fix if you rely on the previous public API structure.
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)
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/encode/httpx/pull/849
First fixed release: 0.13.0
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- Do not use this fix if you rely on the previous public API structure.
- 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.
- Track RSS + object counts after deployments; alert on monotonic growth and GC pressure.
- Add a long-running test that repeats the failing call path and asserts stable memory.
Version Compatibility Table
| Version | Status |
|---|---|
| 0.13.0 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.