The Fix
Upgrade to version 0.18.0 or later.
Based on closed encode/httpx issue #1441 · 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%.
@@ -237,3 +237,9 @@ async with httpx.AsyncClient(transport=transport, base_url="http://testserver")
See [the ASGI documentation](https://asgi.readthedocs.io/en/latest/specs/www.html#connection-scope) for more details on the `client` and `root_path` keys.
+
+## Startup/shutdown of ASGI apps
+
Option A — Upgrade to fixed release\nUpgrade to version 0.18.0 or later.\nWhen NOT to use: This fix is not suitable if you require HTTPX to manage ASGI lifecycle events directly.\n\n
Why This Fix Works in Production
- Trigger: As discussed in #350, HTTPX doesn't provide a solution for managing the startup/shutdown lifecycle of an ASGI app. That is left to user code and not planned to…
- Mechanism: HTTPX does not manage the startup/shutdown lifecycle of ASGI apps, leaving it to user code
- Why the fix works: Added documentation for managing the startup and shutdown lifecycle of ASGI apps, suggesting the use of asgi-lifespan. (first fixed release: 0.18.0).
- 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
- HTTPX does not manage the startup/shutdown lifecycle of ASGI apps, leaving it to user code
- Production symptom (often without a traceback): As discussed in #350, HTTPX doesn't provide a solution for managing the startup/shutdown lifecycle of an ASGI app. That is left to user code and not planned to change soon.
Proof / Evidence
- GitHub issue: #1441
- Fix PR: https://github.com/encode/httpx/pull/1554
- First fixed release: 0.18.0
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.71
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“Seems reasonable yup. I don't think we'll ever want HTTPX to deal with ASGI startup/shutdown, seems out of scope. Also, at some point it'd make…”
Failure Signature (Search String)
- As discussed in #350, HTTPX doesn't provide a solution for managing the startup/shutdown lifecycle of an ASGI app. That is left to user code and not planned to change soon.
Copy-friendly signature
Failure Signature
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As discussed in #350, HTTPX doesn't provide a solution for managing the startup/shutdown lifecycle of an ASGI app. That is left to user code and not planned to change soon.
Error Message
Signature-only (no traceback captured)
Error Message
-------------
As discussed in #350, HTTPX doesn't provide a solution for managing the startup/shutdown lifecycle of an ASGI app. That is left to user code and not planned to change soon.
What Broke
Users may face issues managing ASGI app lifecycles, leading to improper startup/shutdown behavior.
Why It Broke
HTTPX does not manage the startup/shutdown lifecycle of ASGI apps, leaving it to user code
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
Upgrade to version 0.18.0 or later.
Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.
Fix reference: https://github.com/encode/httpx/pull/1554
First fixed release: 0.18.0
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix is not suitable if you require HTTPX to manage ASGI lifecycle events directly.
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 |
|---|---|
| 0.18.0 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.