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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.

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Claude Code v2.1.221

Windows sandbox helpers throw typed errors with reason codes

Under the hood
Useful2 Signal0
Windows

Windows sandbox failures now carry a reason code, though the message you see is unchanged.

What

Bare error throws in the Windows sandbox helper were replaced with a dedicated WindowsSandboxError carrying a machine-readable code, and for srt-win calls the subcommand as well.

Details
  • Codes include acl_grant_failed, srt_win_not_found, srt_win_timeout, srt_win_nonzero, spawn_failed, bin_shell_invalid, srt_win_bad_json, wfp_verify_bind_failed, wfp_verify_unparseable and acl_stamp_failed. None of these appear in 2.1.220.
  • Message text is unchanged, so what a user sees is the same; only the structure carried alongside it is new.
  • Separately, the helper that rewrites raw sandbox-runtime install advice into Claude Code advice now returns the message untouched when the platform is not Windows.
Evidence

bin_shell_invalid, acl_grant_failed

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.221 →