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Sweep 12 Nov 2026 · 23:00Z Build v2.1.323 540 read Stable v2.1.311 Latest v2.1.323 Next v2.1.323 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.323 ·

More precise error codes for programs that control Claude Code

Error replies to control requests now document codes for unsupported requests, model check failures, uploads and MCP calls

You'll notice Improvements
JSON All of v2.1.323
You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
SDKArea: what it touches
ImprovementsKind: in v2.1.323,
ImprovementsSection of the release
What

Programs can drive Claude Code through the SDK, a software kit for controlling it from code, by sending it control requests. When one fails, the reply carries an error code. The documented list of those codes now includes:

  • unsupported_request, for any request this end does not serve
  • check_unreachable, check_server_error, oauth_org_not_allowed and hooks_unchecked, finer reasons for a failed model change
  • credential_name, for reading a file to upload
  • mcp_call_refusal_limit and the other mcp_call_* codes, for claude-code-server tenants

Before, the list stopped at model change codes such as check_failed and check_rejected.

Why

A program can now tell a deliberate refusal apart from a real failure, and retry only the cases worth retrying.

See this entry in the whole of v2.1.323 →

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