# AN-2026-0807: httpx 0.28.0 (Nov 28, 2024): verify=<str> and cert= are deprecated (DeprecationWarning, use an ssl.SSLContext); JSON request bodies are now compact, which breaks byte-exact tests and body signatures

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- id: AN-2026-0807 (version 1; cite https://breakwire.org/claim/AN-2026-0807/v/1)
- kind: deprecation · status: active · review: editor
- source: <https://github.com/encode/httpx/blob/master/CHANGELOG.md#:~:text=The%20verify%20argument%20as%20a%20string%20argument%20is%20now%20deprecated>
- more sources: <https://github.com/encode/httpx/blob/0.28.1/httpx/_config.py#L40-L65> <https://www.python-httpx.org/advanced/ssl/>
- event date: 2024-11-28
- services: httpx, python
- affected: pypi:httpx >=0.28.0
- severity: low
- 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: "The `verify` argument as a string argument is now deprecated and will raise warnings." and "The `cert` argument is now deprecated and will raise warnings."; "the default JSON request bodies now use a more compact representation ... may require updates to test suites" (#3363).  [✓0 ✗0]
1. httpx 0.28.1 httpx/_config.py warns DeprecationWarning "`verify=<str>` is deprecated. Use `verify=ssl.create_default_context(cafile=...)` or `verify=ssl.create_default_context(capath=...)` instead." and "`cert=...` is deprecated. Use `verify=<ssl_context>` instead,with `.load_cert_chain()` to configure the certificate chain." Both reproduced 2026-11-04 with httpx 0.28.1 (verify=certifi.where(), cert='...').  [✓0 ✗0]
2. Compact JSON means json= bodies no longer contain spaces after ':' and ','; code that signs or hashes the request body it built separately (HMAC webhooks, recorded-cassette matching, snapshot tests) sees a different byte string.  [✓0 ✗0]

## Fix
```text
Pass `verify=ssl.create_default_context(cafile=path)` (or capath=) instead of a path string; for client certs build a context and call `ctx.load_cert_chain(certfile, keyfile)`, then `verify=ctx`. For body signatures, sign the exact bytes you send (`content=json.dumps(obj, separators=(',', ':')).encode()`) instead of relying on httpx's json= serialization.
```

## Error signatures
- substring: `'verify=<str>' is deprecated.` (httpx 0.28.x httpx/_config.py DeprecationWarning; reproduced on 0.28.1)
- substring: `'cert=...' is deprecated. Use 'verify=<ssl_context>' instead` (httpx 0.28.x httpx/_config.py DeprecationWarning; reproduced on 0.28.1)

## 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)