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●2.1.302 — Fork subagents are now on by default in claude -p, the Agent SDK and the desktop app. Turn them off with CLAUDE_CODE_FORK_SUBAGENT=0 (10/16)●2.1.299 — Conversations over 200K tokens left idle about 54 minutes get compacted; MCP allow rules now match only the server they name●SONNET 4.5 — Retires on the Claude API on 11/30, 43 days left. Migrate to Sonnet 5.5●WINDOWS — Reports say hooks break silently only on Japanese-locale Windows; check the character encoding first●FAST MODE — Opus 5.5 fast mode is out of research preview and no longer needs the beta header (10/15)●NEW — I Put a Ten-Line Promise File at the To…●2.1.302 — Fork subagents are now on by default in claude -p, the Agent SDK and the desktop app. Turn them off with CLAUDE_CODE_FORK_SUBAGENT=0 (10/16)●2.1.299 — Conversations over 200K tokens left idle about 54 minutes get compacted; MCP allow rules now match only the server they name●SONNET 4.5 — Retires on the Claude API on 11/30, 43 days left. Migrate to Sonnet 5.5●WINDOWS — Reports say hooks break silently only on Japanese-locale Windows; check the character encoding first●FAST MODE — Opus 5.5 fast mode is out of research preview and no longer needs the beta header (10/15)●NEW — I Put a Ten-Line Promise File at the To…
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Claude Haiku 3 Deprecation — Migrate by April 19, 2026

Claude HaikudeprecationmigrationAPI

Deprecation Notice

Anthropic has announced that Claude Haiku 3 (claude-3-haiku-20240307) will be retired on April 19, 2026. After this date, API requests to this model will return errors.

Who Is Affected

Developers using claude-3-haiku-20240307 in API calls. Claude.ai users are automatically switched to newer models and are not affected.

Migration Target

The successor model is Claude Haiku 4.5 (claude-haiku-4-5-20251001).

Key Differences

  • Context window: 200K tokens (unchanged)
  • Max output: 64K tokens (up from 4K in Haiku 3)
  • Extended Thinking: Supported (not available in Haiku 3)
  • Pricing: Input $1 / Output $5 per million tokens (higher than Haiku 3 but justified by performance improvements)

Migration Steps

Simply change the model ID in your API code.

# Before
model="claude-3-haiku-20240307"
 
# After
model="claude-haiku-4-5-20251001"
# Or use the alias
model="claude-haiku-4-5"

Things to Watch

  • Haiku 4.5 has much larger max output, so review your max_tokens settings
  • Pricing has changed, so update your cost estimates
  • Enabling Extended Thinking incurs additional costs

Summary

Complete your migration by April 19, 2026. With significantly improved performance, Haiku 4.5 offers substantial benefits.