Anthropic Model Deprecation and Claude Retirement Schedule

Claude Sonnet 4.5 is deprecated and is scheduled to retire from the Claude API on November 30, 2026, with claude-sonnet-5-5 designated as the replacement. At Layer3Labs, we build AI workflow systems for businesses, and model retirements are a routine maintenance task in those builds.

Claude Mythos Preview is also deprecated as of June 9, 2026, though Anthropic has not yet published a final retirement date for that preview snapshot. Multiple earlier generations, including Claude Opus 4.1, Claude Opus 4, Claude Sonnet 4, Claude 3.7 Sonnet, and earlier Claude 3 releases, have already retired and return errors on direct API requests. Active models such as Claude Sonnet 4.6 and the Claude 5 family remain fully supported for production workloads.

Deprecations apply specifically to Anthropic-operated platforms, including the Claude API, Claude Platform on Amazon Web Services (AWS), and Microsoft Foundry. Third-party cloud providers establish independent schedules for hosted Claude snapshots. Developers can verify active model statuses and documentation updates directly on the official Anthropic model deprecations documentation.

Claude Models Being Retired Next

Anthropic has scheduled the retirement of claude-sonnet-4-5-20250929 for November 30, 2026, while claude-mythos-preview remains deprecated with a retirement date to be announced. Claude Sonnet 4.5 entered deprecated status on September 30, 2026. Anthropic lists claude-sonnet-5-5 as the official replacement. Workloads still targeting this snapshot must transition before the November cutoff to prevent API call interruptions.

Claude Mythos Preview entered deprecation on June 9, 2026, without an announced retirement cutoff. Anthropic documentation notes that deprecated models are likely to be less reliable than active models. Teams evaluating preview endpoints should plan migrations toward active production models rather than building long-term dependencies on unfinalized snapshots.

Two active models carry tentative availability floor dates that have arrived or arrive soon. Claude Haiku 4.5 is listed as retiring not sooner than October 15, 2026, and Claude Opus 4.5 not sooner than November 24, 2026. Each date is only the earliest day Anthropic could retire that model. Anthropic has not announced a retirement date for either one. As of October 15, 2026, claude-haiku-4-5-20251001 remains in Active status. You can compare options in the Claude Haiku 5.5 vs Claude Haiku 4.5 comparison or review the Claude Haiku 4.5 guide.

• claude-sonnet-4-5-20250929 (Claude Sonnet 4.5): Deprecated September 30, 2026, retires November 30, 2026 -> replacement claude-sonnet-5-5
• claude-mythos-preview (Claude Mythos Preview): Deprecated June 9, 2026, retirement date to be announced
• claude-haiku-4-5-20251001 (Claude Haiku 4.5): Active status, tentative retirement not sooner than October 15, 2026
• claude-opus-4-5-20251101 (Claude Opus 4.5): Active status, tentative retirement not sooner than November 24, 2026

Retired Claude Models and Replacement Paths

Anthropic has retired all Claude 1, Claude 2, and initial Claude 3 snapshots from the Claude API, directing developers to newer model generations. Models retired during 2026 include several Claude 4 models. Claude Opus 4.1 was deprecated on June 5, 2026, and retired on August 5, 2026, with claude-opus-4-8 designated as the replacement. Claude Opus 4 and Claude Sonnet 4 were deprecated on April 14, 2026, and retired on June 15, 2026, mapping to claude-opus-4-8 and claude-sonnet-5-5 respectively.

Four more models retired earlier in 2026. Claude 3.7 Sonnet was deprecated on October 28, 2025, and retired on February 19, 2026, in favor of claude-sonnet-5-5. Claude 3.5 Haiku was deprecated on December 19, 2025, and retired on February 19, 2026, replaced by claude-haiku-4-5-20251001. Claude 3 Haiku was deprecated on February 19, 2026, and retired on April 20, 2026, also pointing to claude-haiku-4-5-20251001. Claude 3 Opus retired on January 5, 2026, with claude-opus-4-8 as the designated replacement.

Older models retired in 2024 and 2025. Claude 3.5 Sonnet snapshots from June 20, 2024, and October 22, 2024, retired on October 28, 2025, with claude-sonnet-5-5 as the migration target. Claude 2.0, Claude 2.1, and Claude 3 Sonnet snapshots retired on July 21, 2025. The original Claude 1 and Claude Instant model families reached final retirement on November 6, 2024.

• claude-opus-4-1-20250805: Deprecated June 5, 2026, retired August 5, 2026 -> claude-opus-4-8
• claude-opus-4-20250514: Deprecated April 14, 2026, retired June 15, 2026 -> claude-opus-4-8
• claude-sonnet-4-20250514: Deprecated April 14, 2026, retired June 15, 2026 -> claude-sonnet-5-5
• claude-3-7-sonnet-20250219: Deprecated October 28, 2025, retired February 19, 2026 -> claude-sonnet-5-5
• claude-3-haiku-20240307: Deprecated February 19, 2026, retired April 20, 2026 -> claude-haiku-4-5-20251001
• claude-3-5-haiku-20241022: Deprecated December 19, 2025, retired February 19, 2026 -> claude-haiku-4-5-20251001
• claude-3-opus-20240229: Retired January 5, 2026 -> claude-opus-4-8
• claude-3-5-sonnet (20240620 and 20241022): Retired October 28, 2025 -> claude-sonnet-5-5
• claude-2.0, claude-2.1, claude-3-sonnet-20240229: Retired July 21, 2025
• Claude 1 and Claude Instant family: Retired November 6, 2024

Active Claude Models and Earliest Availability Floors

Anthropic maintains fifteen active Claude models across the Claude 4 and Claude 5 generations with tentative retirement dates running as late as October 7, 2027. Active models represent fully supported endpoints recommended for ongoing production deployments. Each active snapshot carries a tentative retirement date written as not sooner than a calendar day. That date is the earliest point Anthropic lists for retiring the model. It is not an announced retirement date.

The Claude 5 generation provides long availability windows extending into mid and late 2027. Claude Fable 5.1 and Claude Mythos 5.1 are listed as retiring not sooner than September 1, 2027. Claude Opus 5.5 is listed as not sooner than September 22, 2027, and Claude Sonnet 5.5 as not sooner than September 28, 2027. Claude Haiku 5.5 has the latest floor, not sooner than October 7, 2027 (see the Claude Haiku 5.5 overview).

Claude 4 generation models remain available for production integrations. Claude Sonnet 4.6 holds an availability floor through February 17, 2027, and Claude Opus 4.6 extends through February 5, 2027. Capabilities and per-token prices for each active model are compared in the Claude models comparison and Claude API pricing breakdown.

• claude-haiku-5-5: Active status, tentative retirement not sooner than October 7, 2027
• claude-sonnet-5-5: Active status, tentative retirement not sooner than September 28, 2027
• claude-opus-5-5: Active status, tentative retirement not sooner than September 22, 2027
• claude-mythos-5-1: Active status, tentative retirement not sooner than September 1, 2027
• claude-fable-5-1: Active status, tentative retirement not sooner than September 1, 2027
• claude-opus-5: Active status, tentative retirement not sooner than July 24, 2027
• claude-sonnet-5: Active status, tentative retirement not sooner than June 30, 2027
• claude-mythos-5: Active status, tentative retirement not sooner than June 9, 2027
• claude-fable-5: Active status, tentative retirement not sooner than June 9, 2027
• claude-opus-4-8: Active status, tentative retirement not sooner than May 28, 2027
• claude-opus-4-7: Active status, tentative retirement not sooner than April 16, 2027
• claude-sonnet-4-6: Active status, tentative retirement not sooner than February 17, 2027
• claude-opus-4-6: Active status, tentative retirement not sooner than February 5, 2027
• claude-opus-4-5-20251101: Active status, tentative retirement not sooner than November 24, 2026
• claude-haiku-4-5-20251001: Active status, tentative retirement not sooner than October 15, 2026

Model Lifecycle Stages and Post-Retirement Behavior

Anthropic classifies each model snapshot into one of four lifecycle states: Active, Legacy, Deprecated, or Retired. Active status designates models that receive full operational support and represent Anthropic's primary recommendations for new integrations. Legacy status applies to models that no longer receive updates and may be deprecated later.

Deprecated status indicates that a model remains functional but is no longer recommended for active development. Each deprecated snapshot gets a recommended replacement and a retirement date, though Claude Mythos Preview's retirement date is still to be announced as of October 15, 2026. Anthropic documentation notes that deprecated models are likely to be less reliable than active models during this phase.

Retired status marks the final shutdown of a model endpoint. Once a snapshot reaches its retirement date, the model becomes unavailable and all API requests to it fail. Anthropic has committed to long-term preservation of model weights, documented under Anthropic deprecation commitments.

• Active: Fully supported and recommended for production integrations.
• Legacy: No longer receives updates and may be deprecated later.
• Deprecated: Fully functional during the notice window but not recommended; carries an assigned replacement and retirement schedule.
• Retired: No longer available, and API calls to it fail.

Deprecation Notice Policies and Hosting Platform Scope

Anthropic provides at least 60 days of advance notice before retiring any publicly released Claude model. Anthropic notifies customers maintaining active deployments through direct emails and updates to official documentation pages.

Published retirement schedules apply strictly to Anthropic-operated platforms. These platforms include the direct Claude API, Claude Platform on Amazon Web Services (AWS), and Microsoft Foundry. Integration teams using these managed services follow the official timeline published on the Anthropic model deprecations documentation.

Independent cloud providers govern their own infrastructure timelines. Amazon Bedrock and Google Cloud set their own retirement schedules for hosted Claude snapshots, meaning availability windows and retirement dates can differ from Anthropic's native dates. You can also compare how other providers structure retirement schedules by reading the OpenAI deprecated models guide, the Gemini model deprecations schedule, and the GPT-5.5 retirement analysis.

Usage Audit Steps and Parameter Deprecations

Developers can identify deprecated model calls by exporting usage reports from the Anthropic Console. Open the Anthropic Console, navigate to the Usage page, and select the Export option. This generates a Comma-Separated Values (CSV) file containing historical traffic broken down by individual API key and model identifier string.

Beyond model identifiers, Anthropic has deprecated specific inference parameters on modern snapshots. The temperature, top_p, and top_k parameters are deprecated for Claude 4.7 and later models, as well as on Claude Mythos Preview. Supplying a non-default value for any of these parameters returns an HTTP 400 error. Migration instructions in the Anthropic model migration guide advise omitting these parameters and guiding model behavior through prompt instructions.

In the official Python Software Development Kit (SDK) version 1.0 and later, Anthropic removed temperature, top_p, and top_k entirely, meaning passing them into client calls raises a TypeError exception. Engineering teams should review active client wrapper libraries, remove deprecated sampling parameters, and test traffic against claude-sonnet-5-5 before the November 30, 2026 retirement cutover.