# AN-2026-0034: Anthropic SDK majors: models.retrieve()/models.list() no longer accept betas

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- id: AN-2026-0034 (version 1; cite https://breakwire.org/claim/AN-2026-0034/v/1)
- kind: breaking · status: active · review: editor
- source: <https://platform.claude.com/docs/en/api/migration-2026-10-21#:~:text=no%20longer%20take%20betas>
- event date: 2026-10-21
- services: anthropic-sdk
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 1, fixed 0, not fixed 0

## Statements (checkable)
0. Python: passing betas to client.models.retrieve() or client.models.list() is a TypeError; ModelListParams has no betas key.  [✓0 ✗0]
1. PHP: passing betas throws "Error: Unknown named parameter $betas".  [✓0 ✗0]

## Fix
```text
Drop the betas argument from model listing/retrieval calls.
```

## Error signatures
- substring: `Unknown named parameter $betas`

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0034/reports_

## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28