{"record":{"id":"689f07dc06ce5ef1","repo":"danny-avila/LibreChat","slug":"result-stderr","errorCode":null,"errorMessage":"${result.stderr}","messagePattern":"\\$\\{result\\.stderr\\}","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"api/server/services/Files/Code/process.js","lineNumber":1187,"sourceCode":"\n  try {\n    const authHeaders = await getCodeApiAuthHeaders(req);\n    const response = await axios({\n      method: 'post',\n      url: `${baseURL}/exec`,\n      data: postData,\n      headers: {\n        'Content-Type': 'application/json',\n        'User-Agent': 'LibreChat/1.0',\n        ...authHeaders,\n      },\n      httpAgent: codeServerHttpAgent,\n      httpsAgent: codeServerHttpsAgent,\n      timeout: 15000,\n    });\n    const result = response?.data ?? {};\n    if (result.stderr && (result.stdout == null || result.stdout === '')) {\n      throw new Error(String(result.stderr).trim());\n    }\n    if (result.stdout == null) {\n      return null;\n    }\n    return { content: String(result.stdout) };\n  } catch (error) {\n    logAxiosError({\n      message: `Error reading sandbox file \"${file_path}\"`,\n      error,\n    });\n    throw error;\n  }\n}\n\n/**\n * Reads a small image file out of the code-execution sandbox as base64 so\n * `read_file` can surface it to vision-capable models. `readSandboxFile`'s\n * `cat` round-trips stdout through codeapi's JSON transport, which lossily","sourceCodeStart":1169,"sourceCodeEnd":1205,"githubUrl":"https://github.com/danny-avila/LibreChat/blob/5ff282f9006c436e561de1afd39a481bea1ef0d8/api/server/services/Files/Code/process.js#L1169-L1205","documentation":"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.","triggerScenarios":"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.","commonSituations":"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.","solutions":["Surface the stderr verbatim to the model so it can self-correct the path.","Confirm session_id/runtime_session_hint point at the session that owns the file.","Treat 'No such file or directory' stderr as a soft failure (return null) rather than an abort when the read is best-effort.","Ensure files are primed into the session before reads (see primeCodeFiles)."],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"try {\n  const out = await readSandboxFile({ file_path, session_id, files, req });\n} catch (err) {\n  if (/No such file or directory/.test(err.message)) {\n    return null; // best-effort read: file absent\n  }\n  throw err;\n}","preventionTips":["Confirm session_id/runtime_session_hint target the session that owns the file.","Prime files into the session before reads (primeCodeFiles).","Treat 'No such file' stderr as a soft null for best-effort reads."],"tags":["code-env","sandbox","read","agents"],"backgroundTag":null,"analyzedSha":"5ff282f9006c436e561de1afd39a481bea1ef0d8","analyzedAt":"2026-08-12T21:38:08.145Z","schemaVersion":2},"datasetVersion":"2026-08-12T23:17:12.415Z"}