n8n-io/n8n · error · Error

Failed to parse ${label} at ${path}: ${msg}

Error message

Failed to parse ${label} at ${path}: ${msg}

What it means

The readJson helper (line 247) reads a file and calls JSON.parse on its contents. When parsing fails, the original SyntaxError message is wrapped with the file path and a human label (e.g. 'test case', 'existing manifest') so the developer knows exactly which file is malformed and why. This is called from multiple sites: test-case loading (line 504), tier-dataset reading (line 423), and existing-manifest reading (line 345).

Source

Thrown at packages/@n8n/instance-ai/evaluations/cli/build-mcp-manifest.ts:253

	}

	mkdirSync(result.outputDir, { recursive: true });
	if (!result.manifestPath) result.manifestPath = join(result.outputDir, 'manifest.json');
	if (!result.logDir) result.logDir = join(result.outputDir, 'logs');
	const base = result.manifestPath.replace(/\.json$/, '');
	result.statsPath = `${base}-stats.json`;
	mkdirSync(result.logDir, { recursive: true });

	return { helpRequested: false, args: result };
}

function readJson(path: string, label: string): unknown {
	const content = readFileSync(path, 'utf-8');
	try {
		return JSON.parse(content);
	} catch (error) {
		const msg = error instanceof Error ? error.message : String(error);
		throw new Error(`Failed to parse ${label} at ${path}: ${msg}`);
	}
}

function nextArg(argv: string[], i: number, flag: string): string {
	const value = argv[i + 1];
	if (value === undefined || value.startsWith('--')) {
		throw new Error(`Missing value for ${flag}`);
	}
	return value;
}

function parseIntArg(argv: string[], i: number, flag: string): number {
	const raw = nextArg(argv, i, flag);
	const parsed = parseInt(raw, 10);
	if (Number.isNaN(parsed)) throw new Error(`Invalid integer for ${flag}`);
	return parsed;
}

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Open the file at the path shown in the error and fix the JSON syntax error described in the message
2. If it is a truncated manifest from a crashed run, delete it and re-run (or use --manifest with a fresh path)
3. Restore a corrupt test case from git: git checkout -- <path>
4. Validate the file with a JSON linter: npx prettier --check <path> or jq . <path>

// Pre-validate JSON files before the CLI reads them:
import { readFileSync } from 'fs';
function assertValidJson(path: string): void {
  try {
    JSON.parse(readFileSync(path, 'utf-8'));
  } catch (e) {
    throw new Error(`Pre-check failed: ${path} is not valid JSON: ${(e as Error).message}`);
  }
}

try {
  const data = JSON.parse(content);
} catch (error) {
  const msg = error instanceof Error ? error.message : String(error);
  throw new Error(`Failed to parse ${label} at ${path}: ${msg}`);
}

When it happens

Trigger: A test case JSON file (data/workflows/*.json), the manifest file, or any JSON read by the CLI contains invalid JSON syntax — trailing comma, unquoted keys, truncated content from a partial write, BOM character, or corrupted encoding.

Common situations: A previous build run crashed mid-write leaving a truncated JSON file. A hand-edited test case has a syntax error. A merge conflict left conflict markers inside a JSON file. An encoding issue introduced a BOM or control characters.

Understand the failure class

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

Related errors

• Existing manifest at ${manifestPath} is malformed; remove or
• Workflow directory not found: ${workflowDir}
• --build-cwd directory does not exist: ${args.buildCwd}
• Invalid skill at ${sourceDirectory}: ${errors.join('; ')}
• File too large: ${stat.size} bytes (max ${MAX_FILE_SIZE} byt

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/b44e31a24fc2153d. Report an issue: GitHub.