Failed to parse at

Error message

Failed to parse ${label} at ${filePath}: ${error.message}

What it means

readJsonObject in the Cursor project install target reads a JSON config file (e.g. a Cursor settings or MCP file) and, if the file is missing, unreadable, or not valid JSON, throws with the file path and the underlying parse error. Unlike plain JSON.parse errors, this one tells you which labeled file in the install operation failed.

Solutions

Open the file at the path in the message and fix the JSON syntax error named in error.message
If the file is JSONC (with comments), strip comments or move the config to a plain-JSON location before installing
If unreadable due to permissions, fix chmod/chown on the file
If the file is beyond repair, back it up and delete it so the installer can create a fresh one

Example fix

// before: .cursor/mcp.json with a trailing comma
{ "mcpServers": { "context7": { "command": "npx", } } }
// after
{ "mcpServers": { "context7": { "command": "npx" } } }

Defensive patterns

Strategy: try-catch

Validate before calling

// Pre-flight: ensure the destination file is valid JSON before install
try {
  JSON.parse(fs.readFileSync(cursorConfigPath, 'utf8'));
} catch (e) {
  console.error(`Fix ${cursorConfigPath} before installing: ${e.message}`);
}

Type guard

function isPlainObject(v) {
  return v !== null && typeof v === 'object' && !Array.isArray(v);
}

Try / catch

try {
  runInstallOperation(op);
} catch (e) {
  if (/Failed to parse .* at .*:/.test(e.message)) {
    // point the user at the file path in the message to fix its JSON
  } else throw e;
}

Prevention

Keep Cursor config files as strict JSON — no comments or trailing commas
Run `node -e "JSON.parse(...)` on config files after hand edits
Avoid interrupting installs; a partial write leaves unparseable JSON
Editor plugins that lint JSON catch this before the installer does

When it happens

Trigger: createJsonMergeOperation for a Cursor project target encounters a destination file that exists but contains invalid JSON (trailing commas, comments, truncation) or cannot be read (permissions/ENOENT on a path expected to exist for merging).

Common situations: A Cursor config file was hand-edited with JSONC-style comments; a crashed editor or install left a half-written file; the file was saved with a BOM or encoding issue that breaks JSON.parse.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/83c1963c5d929ed3. Report an issue: GitHub.

Appendix: source

Thrown at scripts/lib/install-targets/cursor-project.js:28

  isForeignPlatformPath,
} = require('./helpers');

function toCursorRuleFileName(fileName, sourceRelativeFile) {
  if (path.basename(sourceRelativeFile).toLowerCase() === 'readme.md') {
    return null;
  }

  return fileName.endsWith('.md')
    ? `${fileName.slice(0, -3)}.mdc`
    : fileName;
}

function readJsonObject(filePath, label) {
  let parsed;
  try {
    parsed = JSON.parse(fs.readFileSync(filePath, 'utf8'));
  } catch (error) {
    throw new Error(`Failed to parse ${label} at ${filePath}: ${error.message}`);
  }

  if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
    throw new Error(`Invalid ${label} at ${filePath}: expected a JSON object`);
  }

  return parsed;
}

function createJsonMergeOperation({ moduleId, repoRoot, sourceRelativePath, destinationPath }) {
  const sourcePath = path.join(repoRoot, sourceRelativePath);
  if (!fs.existsSync(sourcePath) || !fs.statSync(sourcePath).isFile()) {
    return null;
  }

  return createManagedOperation({
    kind: 'merge-json',
    moduleId,

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