Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.275 ·

Offline/fallback model catalog switches ccr/ccd default model from Sonnet 4.6 to claude-opus-5

Fallback model list now defaults 'ccr' and 'ccd' to claude-opus-5 instead of Sonnet 4.6 when the live catalog is unreachable

TierYou'll noticehow much it should matter to you
Useful3my rating, 1 to 5
Signal2worth watching, 1 to 5
AreaModelswhat it touches
KindImprovementsin v2.1.275,
You'll notice

Fallback model list now defaults 'ccr' and 'ccd' to claude-opus-5 instead of Sonnet 4.6 when the live catalog is unreachable

What

Claude Code ships a signed, static backup list of models to use if it can't fetch the live model catalog. In this release, the default model for two of the listed surfaces, 'ccr' and 'ccd', changed from claude-sonnet-4-6 to claude-opus-5. The 'cc' surface entry was already set to claude-opus-5 and is unchanged.

Why

If Claude Code ever falls back to this offline catalog, users on the 'ccr' and 'ccd' surfaces will now get claude-opus-5 by default instead of claude-sonnet-4-6.

Read from
Names in the bundleclaude-opus-5
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up claude-opus-5, on claude-in-microsoft-foundry. | Claude Opus 5 | `claude-opus-5` | ✓ | ✓ | build-with-claude/claude-in-microsoft-foundry see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up claude-opus-5, on claude-in-microsoft-foundry.

See this entry in the whole of v2.1.275 →