Anthropic API breaking changes (2026): complete tracker and fixes

Q: How do I check if my codebase is affected by Anthropic breaking changes?

Run npx mendapi scan in your repo. It statically matches your files against the 4 Anthropic breaking changes and deprecations in this tracker and reports file, line and confidence for every hit — locally, in about 30 seconds, with zero network calls.

Q: How many Anthropic API breaking changes are on record?

This tracker records 4 entries for Anthropic (4 breaking changes and 0 deprecations, 2026). Each entry is adjudicated: 1 is code-fixable, 1 require a decision no codemod can make, and 2 are unclear — documented too thinly to rule a codemod in or out, so they stay in the coverage denominator.

Q: Are there automated fixes for Anthropic breaking changes?

Not yet as a deterministic pack. Code-fixable entries above carry reviewed migration guidance, and the optional BYO-LLM mode can draft patches on your own compute — nothing is applied without your review.

Q: Does my code get uploaded when scanning for Anthropic changes?

No. mendapi scan, deps and fix run with zero network code, mechanically enforced by the test suite. Optional hosted reporting is metadata-only, secrets-redacted, and requires an explicit flag.

anthropic 4 breaking / deprecation entries 2026

Anthropic ships API and SDK changes continuously. Most are additive — but the ones that are not can silently break integrations that worked yesterday. This page is the complete, continuously regenerated record of every Anthropic breaking change and deprecation in the mendapi change database: 4 entries (4 breaking, 0 deprecation), each linked to its upstream source and, where possible, to a concrete fix.

How to read this page

Every entry carries a fixability verdict from the mendapi adjudication pipeline: code-fixable means a mechanical code change repairs the break (1 entries); not code-fixable means the change requires a business decision, credential provisioning, or upstream action that no codemod can produce (1 entries). Entries marked auto-fix pack have a deterministic, gold-tested migration pack that mendapi fix can apply locally.

Am I affected?

Reading a changelog tells you what changed — not whether your code uses the affected surface. The mendapi scanner answers that locally, in about 30 seconds, without any code leaving your machine:

npx mendapi sync
# -> one network call: pulls the change feed into a local database
npx mendapi scan
# -> N findings: file, line, provider, confidence
mendapi deps --match
# -> which of the changes below actually hit your endpoints

See Getting Started for the full workflow and the security model for why zero code upload is the default and only mode.

Complete Anthropic breaking change timeline

Date	Change	Ref
2026-08-07	sdk: v0.116.0 breaking	source
2026-08-07	v0.121.0 breaking anthropic-sdk-python v0.121.0: the only removal is 'api: remove retired Claude Opus 4.1 models'	source
2026-07-20	aws-sdk: v0.6.1 breaking not code-fixable	source
2026-07-01	v0.115.1 breaking code-fixable Commit 5e7c431 verified file by file via GitHub commits API: 8 nonfunctional beta webhook event data type modules	source

Automated migration packs for Anthropic

No deterministic pack ships for Anthropic yet; code-fixable entries above carry reviewed migration guidance, and BYO-LLM draft fixes can generate patch drafts on your own compute.

Recent Anthropic releases adjudicated non-breaking

Not paging you is the other half of the job. The same pipeline that produced the timeline above also cleared 20 Anthropic changes as additive or fix-only — releases an integrator can upgrade through without a migration. The most recent:

Date	Release	Ref
2026-08-07	aws-sdk: v0.6.2 fix	source
2026-08-07	bedrock-sdk: v0.32.1 fix	source
2026-08-07	foundry-sdk: v0.4.1 fix	source
2026-08-07	google-cloud-sdk: v0.0.7 fix	source
2026-08-07	vertex-sdk: v0.19.1 fix	source
2026-07-28	v0.120.1 fix mcp: pin mcp extra to <2	source
2026-07-28	v0.120.2 fix mcp: support mcp sdk v2 alongside v1	source
2026-07-24	v0.120.0 additive api: add claude-opus-5 model	source

Monitoring Anthropic going forward

This page is regenerated from the change database, which is fed by release feeds, changelog capture and OpenAPI spec diffing — so it does not depend on Anthropic writing a perfect changelog. mendapi monitors 84125 change records across 20 providers; hosted plans watch your repos continuously and open fix PRs when a change lands. See pricing.

Frequently asked questions

How do I check if my codebase is affected by Anthropic breaking changes?