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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.305 ·

Device-tool refusal now names the nested user namespaces sandbox setting

The message about device tools being withheld now lists sandbox.allowNestedUserNamespaces among the settings that weaken isolation

You'll notice Improvements
JSON All of v2.1.305
You'll noticeTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
SandboxArea: what it touches
ImprovementsKind: in v2.1.305,
ImprovementsSection of the release

Unclear Whether turning on the setting now actually withholds device tools, or only the message text changed, is not clear.

What

When the sandbox (the fenced-off area where Claude Code runs commands with limits) has been weakened by a setting, the device serves no device tools and shows a message listing the settings that cause this. That list now includes sandbox.allowNestedUserNamespaces, placed between sandbox.allowAppleEvents and sandbox.enableWeakerNestedSandbox.

Why

If you turn on sandbox.allowNestedUserNamespaces, expect it to count as weakening the sandbox, which can leave the device with no device tools.

Read from
Names in the bundlesandbox.allowNestedUserNamespaces
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 sandbox.allowNestedUserNamespaces, on Configure the sandboxed Bash tool. * To keep Chromium's or Electron's own sandbox, or to run a nested bubblewrap or `unshare`, set [`sandbox.allowNestedUserNamespaces`](/docs/en/settings-reference#sandbox-allownestedusernamespaces) to `true` in `~/.claude/settings.json`, no… sandboxing see the edit
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhether turning on the setting now actually withholds device tools, or only the message text changed, is not clear.
Anthropic's documentation agreesAnthropic's documentation has since written up sandbox.allowNestedUserNamespaces, on Configure the sandboxed Bash tool.
Anthropic's release notes agreeAdded sandbox.allowNestedUserNamespaces so sandboxed commands on Linux can create user namespaces (Chromium, rootless podman); this lets…

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