starlette Eight tests fail when running the test suite with

The Fix

Upgrade to version 0.17.0 or later.

Based on closed Kludex/starlette issue #1293 · PR/commit linked

Open PR/Commit

@@ -29,6 +29,8 @@ filterwarnings=
     ignore: The 'context' alias has been deprecated. Please use 'context_value' instead\.:DeprecationWarning
     ignore: The 'variables' alias has been deprecated. Please use 'variable_values' instead\.:DeprecationWarning
+    # Workaround for Python 3.9.7 (see https://bugs.python.org/issue45097)
+    ignore:The loop argument is deprecated since Python 3\.8, and scheduled for removal in Python 3\.10\.:DeprecationWarning:asyncio

fix.md

Option A — Upgrade to fixed release\nUpgrade to version 0.17.0 or later.\nWhen NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.\n\n

Why This Fix Works in Production

Trigger: Eight tests fail when running the test suite with Python 3.9.7
Mechanism: Addresses deprecation warnings in Python 3.9.7, which were causing test failures.
Why the fix works: Addresses deprecation warnings in Python 3.9.7, which were causing test failures. (first fixed release: 0.17.0).

Why This Breaks in Prod

Shows up under Python 3.9.7 in real deployments (not just unit tests).
Production symptom (often without a traceback): Eight tests fail when running the test suite with Python 3.9.7

Proof / Evidence

GitHub issue: #1293
Fix PR: https://github.com/encode/starlette/pull/1287
First fixed release: 0.17.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.62

Discussion

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

Jump to Sources Open on GitHub

“Already solved on https://github.com/encode/starlette/pull/1287”

@Kludex · 2021-09-27 · source

Failure Signature (Search String)

Eight tests fail when running the test suite with Python 3.9.7
[ 31s] =================================== FAILURES ===================================

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Eight tests fail when running the test suite with Python 3.9.7
[   31s] =================================== FAILURES ===================================

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Eight tests fail when running the test suite with Python 3.9.7
[   31s] =================================== FAILURES ===================================

Environment

Python: 3.9.7

What Broke

Eight tests fail when running the test suite, impacting the packaging process.

Fix Options (Details)

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

Upgrade to version 0.17.0 or later.

When NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.

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

Fix reference: https://github.com/encode/starlette/pull/1287

First fixed release: 0.17.0

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

When NOT to Use This Fix

Do not use if it changes public behavior or if the failure cannot be reproduced.

Did This Fix Work in Your Case?

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

Prevention

Add a TLS smoke test that performs a real handshake in CI (include CA bundle validation and hostname checks).
Alert on handshake failures by error string and endpoint to catch cert/CA changes quickly.
Add a stress test that runs high-concurrency workloads and fails on thread dumps / blocked locks.
Enable watchdog dumps in prod (faulthandler, thread dump endpoint) to capture deadlocks quickly.

Version Compatibility Table

Version	Status
0.17.0	Fixed

Related Issues

No related fixes found.

Cluster: starlette:ssl-handshake 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.

starlette Eight tests fail when running the test suite with Python 3.9.7 (Fix)