httpx Support header comparisons with dict / list. (Fix)

The Fix

Upgrade to version 0.15.4 or later.

Based on closed encode/httpx issue #1325 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -724,9 +724,11 @@ def __len__(self) -> int:
 
     def __eq__(self, other: typing.Any) -> bool:
-        if not isinstance(other, Headers):
+        try:
+            other_headers = Headers(other)

repro.py

def __eq__(self, other: typing.Any) -> bool:
    try:
        other_headers = Headers(other)
    except ValueError:
        return False
    return sorted(self._list) == sorted(other_headers._list)

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 0.15.4 or later.\nWhen NOT to use: This fix should not be used if strict type checking for headers is required.\n\n

Why This Fix Works in Production

Trigger: assert response.status_code == 200
Mechanism: The equality method for headers did not support comparisons with dicts or lists
Why the fix works: Supports header comparisons with dicts or lists, allowing for simpler assertions in tests. (first fixed release: 0.15.4).

Why This Breaks in Prod

The equality method for headers did not support comparisons with dicts or lists
Production symptom (often without a traceback): assert response.status_code == 200

Proof / Evidence

GitHub issue: #1325
Fix PR: https://github.com/encode/httpx/pull/1326
First fixed release: 0.15.4
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.68

Discussion

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

Jump to Sources Open on GitHub

“We should support direct header comparisons with dicts, or with lists of two-tuples. This would be nice because it would help folks clean up test cases, eg... The fix will be something like changing Headers.__eq__ from this... To this... A”

Issue thread · issue description · source

Failure Signature (Search String)

assert response.status_code == 200
assert response.text == "Hello, world!"

Copy-friendly signature

signature.txt

Failure Signature
-----------------
assert response.status_code == 200
assert response.text == "Hello, world!"

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
assert response.status_code == 200
assert response.text == "Hello, world!"

Minimal Reproduction

repro.py

def __eq__(self, other: typing.Any) -> bool:
    try:
        other_headers = Headers(other)
    except ValueError:
        return False
    return sorted(self._list) == sorted(other_headers._list)

What Broke

Users faced issues when asserting header equality in tests, leading to false negatives.

Why It Broke

The equality method for headers did not support comparisons with dicts or lists

Fix Options (Details)

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

Upgrade to version 0.15.4 or later.

When NOT to use: This fix should not be used if strict type checking for headers is required.

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/1326

First fixed release: 0.15.4

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

When NOT to Use This Fix

This fix should not be used if strict type checking for headers is required.

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
0.15.4	Fixed

Related Issues

No related fixes found.

Cluster: httpx:other All hubs All clusters

Related clusters: Configuration error Data consistency Timeout

Sources

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