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A new error clearly tells you to update Claude Code when your build is too old for a request.
The API error schema gains a new claude_code_version_too_old error code, sent when the API refuses a request because the Claude Code build is below a required minimum, whether a model-specific floor or an org-policy floor. The error's message text carries the details, and the remedy is updating Claude Code.
Names in the bundleclaude_code_version_too_old