# AN-2026-0806: openai-python < 1.55.3 with httpx >= 0.28 (Nov 28, 2024): OpenAI() / AsyncOpenAI() fail at construction with TypeError unexpected keyword argument 'proxies'; fixed in openai 1.55.3

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- id: AN-2026-0806 (version 1; cite https://breakwire.org/claim/AN-2026-0806/v/1)
- kind: breaking · status: active · review: editor
- source: <https://github.com/openai/openai-python/blob/main/CHANGELOG.md#:~:text=compat%20with%20new%20httpx%200.28.0%20release>
- more sources: <https://github.com/encode/httpx/blob/master/CHANGELOG.md#:~:text=The%20deprecated%20proxies%20argument%20has%20now%20been%20removed> <https://pypi.org/project/openai/1.55.3/>
- event date: 2024-11-28
- services: openai-sdk, httpx, python
- affected: pypi:openai <1.55.3 with httpx >=0.28.0
- severity: high
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. openai-python CHANGELOG (opened 2026-11-04), 1.55.3 (2024-11-28), Bug Fixes: "client: compat with new httpx 0.28.0 release (#1904)"; the same day httpx 0.28.0 removed the deprecated `proxies` argument.  [✓0 ✗0]
1. Reproduced 2026-11-04 on CPython 3.12: openai 1.55.2 + httpx 0.28.1 -> openai.OpenAI(api_key=...) raises TypeError "Client.__init__() got an unexpected keyword argument 'proxies'" and AsyncOpenAI the AsyncClient variant, before any request is made; openai 1.55.3 with the same httpx constructs fine.  [✓0 ✗0]
2. The trigger is usually an unpinned `pip install` that pulls the newest httpx next to an old pinned openai (or a framework that pins openai < 1.55.3).  [✓0 ✗0]

## Fix
```text
Upgrade openai to >= 1.55.3 (`pip install -U openai`). If openai must stay pinned, pin `httpx<0.28` next to it. Note openai >= 3.0.0 uses httpx2 instead of httpx (see the OpenAI SDK HTTPX2 claim).
```

## Outcome reports (0)
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## History
- v1 2026-11-04 by wire-editor: filed from primary sources opened 2026-11-04 (httpx/httpx2/openai-python/anthropic-sdk-python changelogs + source, reproduced locally)