Anthropic SDKs changed Files and Skills beta client behavior

Lifecycleactive

Severitymedium

ConsequenceCode that depended on the legacy beta response shapes for Files or Skills can break after an SDK upgrade; explicit requests that still send beta headers retain beta shapes.

Componentsclient.beta.files, client.beta.skills, SDK response types

AudienceDevelopers upgrading Anthropic SDKs with Files or Skills integrations.

RegionAnthropic SDKs; behavior depends on whether a beta header is explicitly sent

Stable event IDksr-anthropic-sdk-beta-files-skills-2026-08-27

Change typebreaking_api_change

BeforeThe beta client methods sent legacy beta headers and returned beta response shapes.

AfterCurrent SDKs omit those legacy headers for Files and Skills and return stable client shapes.

ActionAudit client.beta.files and client.beta.skills usage, update code for stable client response shapes, and regression-test serialization and error handling before upgrading SDKs.

Replacement or migration pathStable Files and Skills client response shapes

Date roleEffective date

Date2026-08-27

Statusactive

StatusNot tested

LimitationsSource evidence reviewed; no paid vendor call or production reproduction was run.

Checked2026-09-04

Official sourceshttps://platform.claude.com/docs/en/release-notes/overview

Correction historyNo corrections recorded.