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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.91 Home All releases olderv2.1.90 v2.1.92newer
Claude Code v2.1.91

Sandbox Unavailable Error in Stream-JSON Mode

What

When running in headless mode (--output-format stream-json) and the sandbox is required but unavailable, Claude Code now emits a proper JSON error result instead of only writing to stderr.

Details
  • Error message includes: "Sandbox required but unavailable: {reason}. Set sandbox.failIfUnavailable=false to allow unsandboxed execution."
  • The JSON result includes all standard fields (session_id, uuid, duration, etc.) for proper parsing by automation tools
Evidence

Headless sandbox error handling (search for "Sandbox required but unavailable:")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.91 →