# AN-2026-0805: httpx 0.28.0 (Nov 28, 2024) removed the deprecated `proxies` and `app` arguments: Client(proxies=...) / AsyncClient(app=...) now raise TypeError (unexpected keyword argument 'proxies' / 'app')

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- id: AN-2026-0805 (version 1; cite https://breakwire.org/claim/AN-2026-0805/v/1)
- kind: breaking · status: active · review: editor
- source: <https://github.com/encode/httpx/blob/master/CHANGELOG.md#:~:text=The%20deprecated%20proxies%20argument%20has%20now%20been%20removed>
- more sources: <https://github.com/encode/httpx/blob/0.27.2/httpx/_client.py#L676-L690> <https://pypi.org/project/httpx/0.28.0/>
- event date: 2024-11-28
- services: httpx, python
- affected: pypi: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. httpx CHANGELOG (opened 2026-11-04), 0.28.0 (28th November, 2024): "The deprecated `proxies` argument has now been removed." and "The deprecated `app` argument has now been removed." 0.26.0 (20th December, 2023) deprecated `proxies` in favour of the new `proxy` argument or `mounts=`; 0.27.0 (21st February, 2024) deprecated the `app=...` shortcut in favour of `transport=httpx.WSGITransport()` / `transport=httpx.ASGITransport()`.  [✓0 ✗0]
1. On httpx 0.26-0.27 the same calls only warned: DeprecationWarning "The 'proxies' argument is now deprecated. Use 'proxy' or 'mounts' instead." and "The 'app' shortcut is now deprecated. Use the explicit style 'transport=WSGITransport(app=...)' instead." (httpx 0.27.2 httpx/_client.py).  [✓0 ✗0]
2. Reproduced 2026-11-04 with httpx 0.28.1 (latest stable on PyPI; 1.0 is still dev pre-releases) on CPython 3.12: httpx.Client(proxies=...) raises TypeError "Client.__init__() got an unexpected keyword argument 'proxies'", httpx.AsyncClient(proxies=...) the AsyncClient variant, Client(app=...) / AsyncClient(app=...) "... unexpected keyword argument 'app'", and httpx.get(..., proxies=...) "get() got an unexpected keyword argument 'proxies'". Libraries that passed proxies= internally (e.g. openai-py  [✓0 ✗0]

## Fix
```text
Use `proxy="http://host:port"` (single proxy) or `mounts={"https://": httpx.HTTPTransport(proxy=...)}` (per-scheme), and `transport=httpx.ASGITransport(app=app)` / `httpx.WSGITransport(app=app)` instead of `app=`. If the call is inside a dependency, upgrade that dependency; as a stopgap pin `httpx<0.28`.
```

## Error signatures
- substring: `The 'proxies' argument is now deprecated.` (httpx 0.26-0.27 DeprecationWarning (0.27.2 httpx/_client.py L677-679); removed in 0.28.0)
- substring: `The 'app' shortcut is now deprecated.` (httpx 0.27 DeprecationWarning (0.27.2 httpx/_client.py L686-688); removed in 0.28.0)

## 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)