claude-sonnet-4-5-20250929 retirement: the Claude API turns it off on 2026-11-30, replacement claude-sonnet-5-5
As of 2026-10-07, claude-sonnet-4-5-20250929 is Deprecated: Anthropic sent the retirement notice on 2026-09-30, the Claude API retirement date is 2026-11-30, the recommended replacement is claude-sonnet-5-5, and requests after that date fail. GitHub Copilot runs a separate calendar and, per its changelog, removed Sonnet 4.5 from every Copilot surface on 2026-09-01 — do not merge the two dates.
Updated 2026-10-07
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Four dates and ids you can quote
Anthropic API: retirement date
Official table: claude-sonnet-4-5-20250929 is Deprecated, with September 30, 2026 in the Deprecated column and November 30, 2026 as the retirement date. After that day requests fail (Requests to models past the retirement date will fail).
GitHub Copilot removal
GitHub changelog 2026-07-31: Copilot Chat, inline edits, ask/agent, and completions drop Claude Sonnet 4.5 (and 4.6, among others) on 2026-09-01. That is Copilot’s catalog, not the Messages API.
The snapshot id to audit
The bare alias claude-sonnet-4-5 often shows no usage. Hunt the dated snapshot in code. The recommended replacement is claude-sonnet-5-5 (Active on the same table, not sooner than 2027-09-28).
API has entered Deprecated
Anthropic's lifecycle: Active → Legacy → Deprecated (still works, not recommended, replacement + retirement date) → Retired (requests fail). In the 2026-08-28 archived copy of the deprecations page the 4.5 snapshot was still Active (not sooner than 2026-09-29); on 2026-09-30 it moved to Deprecated. Anthropic commits to at least 60 days' notice for public models; this notice ran 61 days (by the official dates, 09-30 → 11-30).
“Retirement” is not one switch
As of 2026-10-07 the Claude API retirement date for claude-sonnet-4-5-20250929 is set: 2026-11-30. Anthropic's deprecation page covers the Claude API, Claude Platform on AWS and Microsoft Foundry; Amazon Bedrock and Google Cloud set their own schedules, so status and dates can differ. GitHub Copilot is a separate catalog: the 2026-07-31 changelog named 2026-09-01 for Gemini 3.1 Pro, Opus 4.5/4.6, Sonnet 4.5/4.6 and Raptor Mini across all Copilot experiences. Same model, two clocks: Copilot removal and API retirement are 90 days apart (by the official dates, 09-01 → 11-30).
2026-09-30: Anthropic sends the Sonnet 4.5 retirement notice
The deprecations page reads: “On September 30, 2026, Anthropic notified developers using Claude Sonnet 4.5 of its upcoming retirement on the Claude API.” The Claude Platform release notes of the same day give 2026-11-30 as the retirement date and recommend migrating to Claude Sonnet 5.5. Projects that still hard-code the 4.5 snapshot should finish migration and regression testing before 2026-11-30 rather than in the final week.
Timeline
GitHub changelog: Upcoming August 2026 model deprecations in GitHub Copilot. Sonnet 4.5 → Claude Sonnet 5; Opus 4.5/4.6 → Opus 4.7 / 4.8 / 5. Individual annual Copilot subscribers keep Sonnet 4.6; monthly and enterprise do not.
Anthropic sends the retirement notice: claude-sonnet-4-5-20250929 becomes Deprecated, Claude API retirement 2026-11-30, recommended replacement claude-sonnet-5-5. In the 2026-08-28 archived copy of the deprecations page it was still Active, not sooner than 2026-09-29.
Claude API retirement date: requests after it fail (Requests to models past the retirement date will fail). Bedrock and Google Cloud follow their own model tables. Re-checked on 2026-10-07: the date is unchanged.
Confirmed vs rumor
Confirmed
Confirmed word for word: the Anthropic deprecations page says “On September 30, 2026, Anthropic notified developers using Claude Sonnet 4.5 of its upcoming retirement on the Claude API”; its table gives November 30, 2026 as the retirement date and claude-sonnet-5-5 as the recommended replacement, and the same page states “Requests to models past the retirement date will fail.” On the Copilot side: GitHub's 2026-07-31 changelog set 2026-09-01 for removing Sonnet 4.5 from Copilot, with Claude Sonnet 5 as the suggested alternative; the annual-individual Sonnet 4.6 carve-out is GitHub's own sentence.
Rumor / misread
“Sonnet 4.5 is already gone from the API” — as of 2026-10-07 it is Deprecated (still callable, not recommended), not Retired; retirement is 2026-11-30. “09-01 was Anthropic's retirement day” — that was Copilot. “11-30 also applies on Bedrock / Google Cloud” — the deprecations page says partner platforms set their own schedules. “Every Copilot user lost Sonnet 4.6 on 09-01” — annual individual plans are exempted.
Migrate per product
Messages API / SDK: switch before 11-30
Export the Console Usage CSV and find claude-sonnet-4-5-20250929 by API key and model. Move to the recommended claude-sonnet-5-5 and regression-test before 2026-11-30. Partner clouds (Bedrock / Google Cloud) may differ — read those tables.
GitHub Copilot: removed on 09-01, use the changelog alternatives
Enterprise admins may need to enable Sonnet 5 / Opus 4.7+ in Copilot model policies. Changelog: no action is required to remove models once deprecated. Annual individuals who still need Sonnet 4.6 should confirm plan type.
Migration order (official mechanism)
① Inventory: export the Console Usage CSV and list the keys still calling claude-sonnet-4-5-20250929. ② Change the id: the first item on the official migration checklist is “Change the model ID to claude-sonnet-5-5” (no date suffix). ③ Change parameters: the migration guide's section on moving from Sonnet 5 applies to every starting model (Every starting model needs the changes in this section) — it includes Sonnet 5.5's five breaking changes, such as forced tool use (tool_choice any / tool) returning a 400 error; this site's Sonnet 5.5 breaking-changes page walks through all five. Coming from Sonnet 4.5 adds more: thinking budget_tokens returns a 400 error on Sonnet 5.5 and must become an effort level, non-default temperature / top_p / top_k must go, assistant prefills must be replaced, and output_format moves to output_config.format. ④ Regress: finish evals on your own tasks before 2026-11-30. On Copilot the removal already happened on 09-01; use the changelog's alternatives. This page does not describe bypassing Copilot model policy or spoofing client identifiers.
What this means on QCode
As of 2026-10-07 both claude-sonnet-4-5-20250929 and claude-sonnet-5-5 are callable on QCode, so one key can run the regression side by side before you shift traffic. QCode follows the official API lifecycle and sets no date of its own: whether the 4.5 snapshot still answers after the official retirement on 2026-11-30 is shown on /models, which lists current model availability. Billing is per token, with each model's unit price on /models. QCode sells API access and does not host GitHub Copilot; Copilot's removal does not change the Messages API lifecycle.
FAQ
Is claude-sonnet-4-5-20250929 already Deprecated?
Yes. Since 2026-09-30 the official table lists it as Deprecated: still callable, not recommended, retirement date 2026-11-30, recommended replacement claude-sonnet-5-5. In the 2026-08-28 archived copy of the page it was still Active, not sooner than 2026-09-29.
Why was Copilot three months earlier?
GitHub schedules the Copilot catalog. The 2026-07-31 changelog set 09-01 across Copilot surfaces; Anthropic's page covers its API and named platforms, where retirement is 2026-11-30. The two dates are 90 days apart (by the official dates) and are allowed to diverge.
Which API id should I move to?
The recommended replacement is claude-sonnet-5-5 (the Recommended replacement column, verbatim). It is Active on the same table, not sooner than 2027-09-28, and the official price table lists $2 input / $10 output against Sonnet 4.5's $3 / $15. claude-sonnet-5 and claude-sonnet-4-6 are also still Active, but they are not Anthropic's recommendation for 4.5. Pick after your own evals; do not only rewrite the string.
Do annual Copilot individuals keep Sonnet 4.6 after 09-01?
GitHub’s words: Claude Sonnet 4.6 remains available to individual GitHub Copilot subscribers on annual plans. Monthly and enterprise are outside that sentence. Sonnet 4.5 has no matching exception.
Is it 2026-11-30 on Bedrock / Google Cloud too?
Not necessarily. The deprecations page says its dates apply to Anthropic-operated platforms (Claude API, Claude Platform on AWS, Microsoft Foundry), while partner-operated platforms (Amazon Bedrock and Google Cloud) set their own retirement schedules, so status and dates can differ. Use those platforms' model tables.
When does QCode stop Sonnet 4.5?
QCode follows the official API lifecycle and sets no separate date: the official retirement is 2026-11-30, and Anthropic states that requests to models past the retirement date will fail. As of 2026-10-07 claude-sonnet-4-5-20250929 is still callable on QCode; migrate hard-coded ids before 11-30 instead of betting on the last day. Model availability is as listed on /models.
Sources
Fetched and checked on 2026-10-07: the model deprecations page on platform.claude.com (Deprecated, November 30, 2026, claude-sonnet-5-5, 60 days' notice, failed requests after retirement), the Claude Platform release notes (2026-09-30 entry), the Sonnet 5.5 migration guide, the official price table and the models overview. The late-August state comes from the Wayback Machine copy of the same page dated 2026-08-28. Copilot 09-01 table: github.blog/changelog/2026-07-31-upcoming-august-2026-model-deprecations-in-github-copilot.
Copilot’s catalog is moving; the API clock is the official table
Replace claude-sonnet-4-5-20250929 with claude-sonnet-5-5 before 2026-11-30; as of 2026-10-07 both ids are callable on QCode, billed per token with unit prices on /models.
Related
Claude Sonnet 5 guide
Copilot’s suggested alternative for Sonnet 4.5, and still Active on the API table.
GPT-5 and o3 snapshots shut down 2026-12-11
Which ID replaces each of the six GPT-5 / o3 snapshots, what to do with aliases, and a migration checklist (official table checked 2026-10-08)
Claude Haiku 4.5
Another dated row on the same table: Haiku 4.5 not sooner than 2026-10-15.
Reading of Anthropic and GitHub public deprecation docs, not a statement by either vendor. Official pages were checked on 2026-10-07; status is whatever the official deprecations table and Copilot changelog say, and model availability is as listed on /models. QCode does not bypass vendor retirements or product policy.