jestjs/jest · error · Error

Cannot parse ${filePath} as JSON: ${error.message}

Error message

Cannot parse ${filePath} as JSON: ${error.message}

What it means

The haste-map worker reads each file ending in package.json and JSON.parses its contents to extract the package `name`. If parsing fails it wraps the underlying SyntaxError into a clear Error naming the offending file path, so a single corrupt package.json does not produce an opaque JSON parse stack. The throw is in worker.ts:60 inside the catch of the JSON.parse try block.

Source

Thrown at packages/jest-haste-map/src/worker.ts:60

    if (content === undefined) {
      content = fs.readFileSync(filePath, 'utf8');
    }

    return content;
  };

  if (filePath.endsWith(PACKAGE_JSON)) {
    // Process a package.json that is returned as a PACKAGE type with its name.
    try {
      const fileData = JSON.parse(getContent());

      if (fileData.name) {
        const relativeFilePath = path.relative(rootDir, filePath);
        id = fileData.name;
        module = [relativeFilePath, H.PACKAGE];
      }
    } catch (error: any) {
      throw new Error(`Cannot parse ${filePath} as JSON: ${error.message}`);
    }
  } else if (!blacklist.has(filePath.slice(filePath.lastIndexOf('.')))) {
    // Process a random file that is returned as a MODULE.
    if (hasteImpl) {
      id = hasteImpl.getHasteName(filePath);
    }

    if (computeDependencies) {
      const content = getContent();
      const extractor = data.dependencyExtractor
        ? await requireOrImportModule<DependencyExtractor>(
            data.dependencyExtractor,
            false,
          )
        : defaultDependencyExtractor;
      dependencies = [
        ...extractor.extract(
          content,

View on GitHub (pinned to f49721c78e)

Solutions

1. Open the path in the error message and validate it with a JSON linter or `node -e "JSON.parse(require('fs').readFileSync('PATH','utf8'))"`.
2. Remove JSON-incompatible syntax (comments, trailing commas, unquoted keys) or rename the file so haste-map does not treat it as package.json.
3. Strip a leading UTF-8 BOM if present.
4. If the file is intentionally JSON5, give it a different name so it is not discovered as a package manifest.

Example fix

// before — package.json with a trailing comma (invalid JSON)
{
  "name": "my-pkg",
  "version": "1.0.0",
}

// after — valid JSON
{
  "name": "my-pkg",
  "version": "1.0.0"
}

import {readFileSync} from 'node:fs';
function assertValidPackageJson(filePath: string) {
  if (!filePath.endsWith('package.json')) return;
  const txt = readFileSync(filePath, 'utf8');
  try { JSON.parse(txt); }
  catch (e) { throw new Error(`${filePath} is not valid JSON: ${(e as Error).message}`); }
}

try {
  JSON.parse(content);
} catch (err) {
  throw new Error(`Cannot parse ${filePath} as JSON: ${(err as Error).message}`);
}

When it happens

Trigger: worker() detects filePath.endsWith(PACKAGE_JSON) (worker.ts:49), reads the file content via graceful-fs, and JSON.parse(getContent()) throws — e.g. trailing commas, comments, BOM, truncation, or a JSON5 file misnamed package.json. The catch at line 59 rethrows as `Cannot parse <filePath> as JSON: <error.message>`.

Common situations: A package.json edited by hand with a trailing comma or comment; a package.json written as JSON5/JSONC; a corrupted/partially-written file from a crashed install; symlinked package.json whose target is empty; BOM-prefixed file from a Windows tool.

Related errors

• There is malformed json in ${packageJsonPath}
• Could not find a "package.json" file in ${rootDir}
• There was an error while parsing the `--config` argument as
• Configuration in ${packageJson} is not valid. Jest expects t
• Crawler retry failed: Original error: ${retryError.message

AI-assisted analysis of jestjs/jest@f49721c78e (2026-08-03). Data as JSON: /data/errors/7b9019af1116773c.json. Report an issue: GitHub.