uvicorn Upgrade `websockets` package (Fix)

The Fix

Upgrade to version 0.11.4 or later.

Based on closed Kludex/uvicorn issue #103 · PR/commit linked

Open PR/Commit

@@ -49,6 +49,66 @@ Run the server:
 ```
 
+# Usage
+
+The uvicorn command line tool is the easiest way to run your application...

fix.md

Option A — Upgrade to fixed release\nUpgrade to version 0.11.4 or later.\nWhen NOT to use: Do not use this fix if you require compatibility with older versions of the `websockets` package.\n\n

Why This Fix Works in Production

Trigger: Currently on 3.3. Unresolved issue with tests hanging on higher versions, see: https://github.com/encode/uvicorn/pull/84
Mechanism: The upgrade of the `websockets` package caused tests to hang due to unresolved issues
Why the fix works: Upgraded the `websockets` package to version 3.3 and made extensive improvements to error handling. (first fixed release: 0.11.4).

Why This Breaks in Prod

The upgrade of the `websockets` package caused tests to hang due to unresolved issues
Production symptom (often without a traceback): Currently on 3.3. Unresolved issue with tests hanging on higher versions, see: https://github.com/encode/uvicorn/pull/84

Proof / Evidence

GitHub issue: #103
Fix PR: https://github.com/encode/uvicorn/pull/84
First fixed release: 0.11.4
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.81

Discussion

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

Jump to Sources Open on GitHub

“Currently on 3.3. Unresolved issue with tests hanging on higher versions, see: https://github.com/encode/uvicorn/pull/84 Needs looking into.  > [!IMPORTANT] > - We're using Polar.sh so you can upvote and hel”

Issue thread · issue description · source

Failure Signature (Search String)

Currently on 3.3. Unresolved issue with tests hanging on higher versions, see: https://github.com/encode/uvicorn/pull/84

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Currently on 3.3. Unresolved issue with tests hanging on higher versions, see: https://github.com/encode/uvicorn/pull/84

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Currently on 3.3. Unresolved issue with tests hanging on higher versions, see: https://github.com/encode/uvicorn/pull/84

What Broke

Tests were hanging, leading to potential delays in deployment and release cycles.

Why It Broke

The upgrade of the `websockets` package caused tests to hang due to unresolved issues

Fix Options (Details)

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

Upgrade to version 0.11.4 or later.

When NOT to use: Do not use this fix if you require compatibility with older versions of the `websockets` package.

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

Fix reference: https://github.com/encode/uvicorn/pull/84

First fixed release: 0.11.4

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

When NOT to Use This Fix

Do not use this fix if you require compatibility with older versions of the `websockets` package.

Did This Fix Work in Your Case?

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

Prevention

Capture the exact failing error string in logs and tests so you can reproduce via a minimal script.
Pin production dependencies and upgrade only with a reproducible test that hits the failing path.

Version Compatibility Table

Version	Status
0.11.4	Fixed

Related Issues

No related fixes found.

Cluster: uvicorn:other All hubs All clusters

Related clusters: Configuration error Data consistency Race condition

Sources

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