httpx Client.close() can hang. (asyncio only). (Fix)

The Fix

Upgrade to version 0.13.0 or later.

Based on closed encode/httpx issue #634 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -1,7 +1,6 @@
 import functools
 import ssl
-import sys
 import typing

repro.py

import asyncio

import httpx


async def main():
    async with httpx.Client() as client:
        response = await client.post(
            "https://login.microsoftonline.com/common/oauth2/v2.0/token",
            # You can keep those parameters, the issue happens also for 4XX responses
            data={
                "grant_type": "authorization_code",
                "code": "code",
                "redirect_uri": "http://localhost:8000/redirect",
                "client_id": "CLIENT_ID",
                "client_secret": "CLIENT_SECRET",
            },
        )

        print(response.http_version)  # HTTP/1.1
        print(len(response.content))  # 485 (same as in Content-Length header)
        print(response.headers)
    # Never happens
    print("Done")
    return response


asyncio.run(main())

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\nUpgrade to version 0.13.0 or later.\nWhen NOT to use: This fix should not be applied if the application relies on waiting for the stream to close explicitly.\n\n

Why This Fix Works in Production

Trigger: await self.close()
Mechanism: The HTTPX client hangs during the closing process due to improper handling of the socket closure
Why the fix works: Addresses the issue where the HTTPX client could hang during the closing process by avoiding the use of wait_closed(). (first fixed release: 0.13.0).

Why This Breaks in Prod

Shows up under Python 3.7 in real deployments (not just unit tests).
The HTTPX client hangs during the closing process due to improper handling of the socket closure
Surfaces as: File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/client.py", line 884, in __aexit__

Proof / Evidence

GitHub issue: #634
Fix PR: https://github.com/encode/httpx/pull/640
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: 0.37

Discussion

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

Jump to Sources Open on GitHub

“Thank you for your feedback @florimondmanca :) I've tried what you suggest (although I have to admit my knowledge on the subject is quite limited):…”

@frankie567 · 2019-12-13 · confirmation · source

“It seems fairly likely this might have been resolved by 0.9.4, just released. Some things to test out here... * Does the issue replicate with…”

@lovelydinosaur · 2019-12-13 · confirmation · source

“> Okay, thanks, that's _super_ helpful - what's the _absolute_ simplest case you can reduce this to? This: > I'm assuming the you wouldn't see…”

@frankie567 · 2019-12-13 · source

“Thank you @tomchristie! * Yes, the issue does replicate with 0.9.4. * No, the issue doesn't replicate with Trio. So, should we suspect a bug…”

@frankie567 · 2019-12-13 · source

Failure Signature (Search String)

await self.close()

Error Message

Stack trace

error.txt

Error Message
-------------
File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/client.py", line 884, in __aexit__
    await self.close()
  File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/client.py", line 873, in close
    await self.dispatch.close()
  File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/dispatch/connection_pool.py", line 212, in close
    await connection.close()
  File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/dispatch/connection.py", line 171, in close
    await self.open_connection.close()
  File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/dispatch/http11.py", line 72, in close
    await self.socket.close()
  File "/Users/fvoron/.local/share/virtualenvs/httpx-oauth-5xgbpDkq/src/httpx/httpx/concurrency/asyncio.py", line 167, in close
    await self.stream_writer.wait_closed()
  File "/Users/fvoron/.pyenv/versions/3.7.5/lib/python3.7/asyncio/streams.py", line 323, in wait_closed
    await self._protocol._closed
  File "/Users/fvoron/.pyenv/versions/3.7.5/lib/python3.7/asyncio/selector_events.py", line 804, in _read_ready__data_received
    data = self._sock.recv(self.max_size)
ConnectionResetError: [Errno 54] Connection reset by peer

Minimal Reproduction

repro.py

import asyncio

import httpx


async def main():
    async with httpx.Client() as client:
        response = await client.post(
            "https://login.microsoftonline.com/common/oauth2/v2.0/token",
            # You can keep those parameters, the issue happens also for 4XX responses
            data={
                "grant_type": "authorization_code",
                "code": "code",
                "redirect_uri": "http://localhost:8000/redirect",
                "client_id": "CLIENT_ID",
                "client_secret": "CLIENT_SECRET",
            },
        )

        print(response.http_version)  # HTTP/1.1
        print(len(response.content))  # 485 (same as in Content-Length header)
        print(response.headers)
    # Never happens
    print("Done")
    return response


asyncio.run(main())

Environment

Python: 3.7
httpx: 0.9.3

What Broke

Clients may experience hanging behavior during the closing of the HTTPX client, leading to unresponsive applications.

Why It Broke

The HTTPX client hangs during the closing process due to improper handling of the socket closure

Fix Options (Details)

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

Upgrade to version 0.13.0 or later.

When NOT to use: This fix should not be applied if the application relies on waiting for the stream to close explicitly.

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/640

First fixed release: 0.13.0

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

When NOT to Use This Fix

This fix should not be applied if the application relies on waiting for the stream to close explicitly.

Verify Fix

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

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
0.13.0	Fixed

Related Issues

No related fixes found.

Cluster: httpx:auth All hubs All clusters

Related clusters: Configuration error Data consistency Other

Sources

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