danny-avila/LibreChat · warning

${result.stderr}

Error message

${result.stderr}

What it means

Thrown by readSandboxFile (Code/process.js) when the sandbox `/exec` of `cat <path>` produced stderr with empty/no stdout — i.e. the file read failed inside the sandbox. The trimmed stderr becomes the error message so the model/caller sees the sandbox's own diagnostic.

Source

Thrown at api/server/services/Files/Code/process.js:1187

  try {
    const authHeaders = await getCodeApiAuthHeaders(req);
    const response = await axios({
      method: 'post',
      url: `${baseURL}/exec`,
      data: postData,
      headers: {
        'Content-Type': 'application/json',
        'User-Agent': 'LibreChat/1.0',
        ...authHeaders,
      },
      httpAgent: codeServerHttpAgent,
      httpsAgent: codeServerHttpsAgent,
      timeout: 15000,
    });
    const result = response?.data ?? {};
    if (result.stderr && (result.stdout == null || result.stdout === '')) {
      throw new Error(String(result.stderr).trim());
    }
    if (result.stdout == null) {
      return null;
    }
    return { content: String(result.stdout) };
  } catch (error) {
    logAxiosError({
      message: `Error reading sandbox file "${file_path}"`,
      error,
    });
    throw error;
  }
}

/**
 * Reads a small image file out of the code-execution sandbox as base64 so
 * `read_file` can surface it to vision-capable models. `readSandboxFile`'s
 * `cat` round-trips stdout through codeapi's JSON transport, which lossily

View on GitHub (pinned to 5ff282f900)

Solutions

1. Surface the stderr verbatim to the model so it can self-correct the path.
2. Confirm session_id/runtime_session_hint point at the session that owns the file.
3. Treat 'No such file or directory' stderr as a soft failure (return null) rather than an abort when the read is best-effort.
4. Ensure files are primed into the session before reads (see primeCodeFiles).

try {
  const out = await readSandboxFile({ file_path, session_id, files, req });
} catch (err) {
  if (/No such file or directory/.test(err.message)) {
    return null; // best-effort read: file absent
  }
  throw err;
}

When it happens

Trigger: cat of a path that does not exist in the sandbox, lacks read permission, or is a directory; the sandbox shell emitted a diagnostic to stderr with nothing on stdout.

Common situations: The model hallucinated a path that was never written; the path is from a prior expired session; the file was created by a different sandbox session than the one this read targeted; permission bits stripped.

Related errors

• ${parsed.error}
• resource_recovery_required
• "${file_path}" changed while being read from the sandbox
• Reading "${file_path}" exceeded the sandbox stdout limit (ch
• Unexpected output while reading image bytes from the sandbox

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/689f07dc06ce5ef1. Report an issue: GitHub.