{"record":{"id":"149fcc143c07883f","repo":"jestjs/jest","slug":"there-was-an-error-while-parsing-the-config-ar","errorCode":null,"errorMessage":"There was an error while parsing the `--config` argument as a JSON string.","messagePattern":"There was an error while parsing the `--config` argument as a JSON string\\.","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"packages/jest-config/src/index.ts","lineNumber":364,"sourceCode":"        ? replaceRootDirInPath(parentConfigDirname, rawOptions.rootDir)\n        : parentConfigDirname;\n      return {config: rawOptions, configPath: null};\n    } else {\n      throw new Error(\n        'Jest: Cannot use configuration as an object without a file path.',\n      );\n    }\n  }\n  if (isJSONString(config)) {\n    try {\n      // A JSON string was passed to `--config` argument and we can parse it\n      // and use as is.\n      const initialOptions = JSON.parse(config);\n      // NOTE: we might need to resolve this dir to an absolute path in the future\n      initialOptions.rootDir = initialOptions.rootDir || packageRootOrConfig;\n      return {config: initialOptions, configPath: null};\n    } catch {\n      throw new Error(\n        'There was an error while parsing the `--config` argument as a JSON string.',\n      );\n    }\n  }\n  if (!readFromCwd && typeof config == 'string') {\n    // A string passed to `--config`, which is either a direct path to the config\n    // or a path to directory containing `package.json`, `jest.config.js` or `jest.config.ts`\n    const configPath = resolveConfigPath(\n      config,\n      process.cwd(),\n      skipMultipleConfigError,\n    );\n    return {config: await readConfigFileAndSetRootDir(configPath), configPath};\n  }\n  // Otherwise just try to find config in the current rootDir.\n  const configPath = resolveConfigPath(\n    packageRootOrConfig,\n    process.cwd(),","sourceCodeStart":346,"sourceCodeEnd":382,"githubUrl":"https://github.com/jestjs/jest/blob/8e6d128e4a278059ecddecaa97400b04c8ae5fd9/packages/jest-config/src/index.ts#L346-L382","documentation":"readInitialOptions treats a --config value that looks like JSON (isJSONString returns true) as an inline JSON config and runs JSON.parse on it (index.ts:355-368). If parsing throws, Jest wraps the failure in this explicit message so the user knows the issue is malformed JSON rather than a missing file.","triggerScenarios":"jest --config '{testMatch: ...}' (unquoted keys, not valid JSON); jest --config '{\"a\":' (truncated); trailing commas; single quotes; comments in the JSON string; a copy-paste where a JS object literal was passed instead of JSON.","commonSituations":"Hand-writing an inline config and using JS object syntax instead of strict JSON; CI variable expansion that truncated the string; quoting bugs across shells; assuming JSONC (comments/trailing commas) is accepted.","solutions":["Validate the JSON with a linter or JSON.parse in a REPL before passing it.","Use double-quoted keys and string values; remove trailing commas and comments.","If the config is large or needs comments, put it in a jest.config.js/.ts file and pass the path instead."],"exampleFix":"// before\njest --config \"{testMatch: ['**/*.test.js']}\"\n// after\njest --config \"{\\\"testMatch\\\":[\\\"**/*.test.js\\\"]}\"","handlingStrategy":"validation","validationCode":"function tryParseJsonConfig(cfg: string): object {\n  try { return JSON.parse(cfg); }\n  catch (e) { throw new Error(`Invalid JSON for --config: ${(e as Error).message}`); }\n}","typeGuard":"function isStrictJson(s: string): boolean {\n  try { JSON.parse(s); return true; } catch { return false; }\n}","tryCatchPattern":null,"preventionTips":["Prefer a config file over inline JSON for anything non-trivial.","Validate inline JSON with a parser before invoking jest.","Use strict JSON (double quotes, no trailing commas, no comments)."],"tags":["jest-config","config","json-parse","cli"],"backgroundTag":null,"analyzedSha":"8e6d128e4a278059ecddecaa97400b04c8ae5fd9","analyzedAt":"2026-08-10T18:11:27.960Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}