claude-mythos-preview to Retire June 30, Migrate to claude-mythos-5

13 Jun 2026 ·3rd Tech Deathwatch entry in 2026

Key facts

Date	13 Jun 2026

Anthropic will retire claude-mythos-preview on June 30, 2026, according to the company’s official Model Deprecations page.

The model has been marked as deprecated, with claude-mythos-5 listed as the recommended replacement. Users currently relying on claude-mythos-preview will need to migrate ahead of the retirement date.

Note that claude-mythos-5 is currently invitation-only and gated behind Project Glasswing.

Source:
Anthropic Model Deprecations page
https://platform.claude.com/docs/en/about-claude/model-deprecations

Exact excerpt:

claude-mythos-preview — Deprecated | Retirement Date: June 30, 2026 | Recommended Replacement: claude-mythos-5

Users should begin planning their migration in the coming weeks.

Everything on record: Anthropic

Narracomm · The Record

Anthropic

Everything Narracomm has filed on Anthropic.

Updated 29 Oct 2026 · Links open our coverage; primaries are cited there

Headline	Date	Coverage
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Anthropic Enforces Hard Retirement for Two Claude 4 Models Today — Sonnet-4-20250514 and Opus-4-20250514 Cut Off June 15, 2026	15 Jun 2026	Read More →
Anthropic Lands OpenAI Custom Chip Engineer Clive Chan	13 Jun 2026	Read More →
Anthropic Deprecates Temperature, Top_P, and Top_K on Newer Opus Models	13 Jun 2026	Read More →
claude-mythos-preview to Retire June 30, Migrate to claude-mythos-5	13 Jun 2026	Read More →
Claude Opus 4 and Sonnet 4 Retirement Deadline Hits This Weekend	13 Jun 2026	Read More →
Anthropic Sets Retirement Dates for Multiple Claude Models	13 Jun 2026	Read More →

Last updated 4 Oct 2026 · Narracomm · The Record · every figure cites its primary above.

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