Diagnose Claude Code sandbox-unavailable errors, distinguish fallback from strict blocking, and recover without disabling isolation blindly.
Originally published at CodeReport Global — read the full guide with code, the decision matrix, and recovery boundaries at https://codereportglobal.indevs.in/articles/claude-code-sandbox-required-unavailable-fail-closed.
Why this matters
If Claude Code reports “sandbox required but unavailable” , do not solve it by turning isolation off and retrying until the command works. First determine which control produced the failure: the sandbox could not start, a command was blocked inside the sandbox, or a resume path consulted an unavailable sandbox…
What you'll get in the full article
- The three questions to answer first
- Why sandbox.failIfUnavailable matters
- Diagnose dependencies without disabling the boundary
- Distinguish strict blocking from unsandboxed fallback
- Investigate resume-only failures as version-scoped bugs
- Copy-paste commands + expected output + common errors
- A clear boundary between documented behavior, issue evidence, and synthetic fixture results
👉 Read the full article: https://codereportglobal.indevs.in/articles/claude-code-sandbox-required-unavailable-fail-closed
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Canonical: https://codereportglobal.indevs.in/articles/claude-code-sandbox-required-unavailable-fail-closed
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