UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'close' of undefined

Learn how to fix the 'Cannot read property close of undefined' error when trying to close a browser or page that doesn't exist

Ivan Muñoz Apr 30, 2025

Crash

This error occurs when you try to call the close() method on a browser or page object that is undefined. This typically happens due to improper initialization or error handling in your automation code.

Common Causes

• Undefined browser/page: Trying to close a non-existent browser or page
• Error before initialization: Error occurs before browser/page is created
• Scope issues: Browser/page variable out of scope
• Async timing issues: Trying to close before initialization completes
• Error handling problems: Not checking if objects exist before closing

Solutions

1. Implement proper initialization checks

let browser;
let page;

async function initialize() {
  try {
    browser = await puppeteer.launch();
    page = await browser.newPage();
    return { browser, page };
  } catch (error) {
    console.error('Initialization failed:', error);
    throw error;
  }
}

async function cleanup() {
  try {
    if (page) await page.close();
    if (browser) await browser.close();
  } catch (error) {
    console.error('Cleanup failed:', error);
  }
}

2. Use safe cleanup functions

async function safeClose(object) {
  if (object && typeof object.close === 'function') {
    try {
      await object.close();
    } catch (error) {
      console.error('Error closing object:', error);
    }
  }
}

// Usage
async function runAutomation() {
  let browser;
  let page;
  
  try {
    browser = await puppeteer.launch();
    page = await browser.newPage();
    // ... your automation code ...
  } catch (error) {
    console.error('Automation failed:', error);
  } finally {
    await safeClose(page);
    await safeClose(browser);
  }
}

3. Implement proper error handling

async function runWithErrorHandling() {
  let browser;
  let page;
  
  try {
    browser = await puppeteer.launch();
    if (!browser) {
      throw new Error('Browser initialization failed');
    }
    
    page = await browser.newPage();
    if (!page) {
      throw new Error('Page creation failed');
    }
    
    await page.goto('https://example.com');
    // ... your automation code ...
  } catch (error) {
    console.error('Error:', error);
    // Clean up any successfully created resources
    if (page) await page.close().catch(console.error);
    if (browser) await browser.close().catch(console.error);
  }
}

4. Use a browser manager class

class BrowserManager {
  constructor() {
    this.browser = null;
    this.page = null;
  }

  async initialize() {
    this.browser = await puppeteer.launch();
    this.page = await this.browser.newPage();
  }

  async cleanup() {
    if (this.page) {
      await this.page.close().catch(console.error);
      this.page = null;
    }
    if (this.browser) {
      await this.browser.close().catch(console.error);
      this.browser = null;
    }
  }
}

// Usage
const manager = new BrowserManager();
try {
  await manager.initialize();
  // ... your automation code ...
} finally {
  await manager.cleanup();
}

5. Implement retry logic with proper checks

async function runWithRetry(maxRetries = 3) {
  let browser;
  let page;
  
  for (let i = 0; i < maxRetries; i++) {
    try {
      browser = await puppeteer.launch();
      page = await browser.newPage();
      await page.goto('https://example.com');
      return { browser, page };
    } catch (error) {
      console.error(`Attempt ${i + 1} failed:`, error);
      // Clean up any partially created resources
      if (page) await page.close().catch(console.error);
      if (browser) await browser.close().catch(console.error);
      if (i === maxRetries - 1) throw error;
    }
  }
}

Still Encountering Issues?

If you’re still having trouble with undefined object errors, you can use a visual testing tool like Buglesstack to debug your automation and track object lifecycle.

// .. assuming you already have your Puppeteer browser and page initialized

try {
	await page.goto('https://www.google.com/search?q=puppeteer');		
	await page.waitForSelector('[name="q"]');
}
catch (error) {
	// Prepare buglesstack data
	const buglesstackData = {
		url: page.url(),
		screenshot: await page.screenshot({ encoding: 'base64' }),
		html: await page.content(),
		metadata: {},
		message: error.message,
		stack: error.stack
	};

	// Get your access token from https://app.buglesstack.com
	const ACCESS_TOKEN = 'HERE_YOUR_ACCESS_TOKEN';

	// Send error to buglesstack
	await axios.post('https://app.buglesstack.com/api/v1/crashes', buglesstackData, {
		headers: {
			Authorization: `Bearer ${ACCESS_TOKEN}`,
			'Content-Type': 'application/json'
		}
	});
		
	// Re-throw the error to propagate it
	throw error;
}

By implementing proper initialization checks and error handling, you can resolve the “Cannot read property ‘close’ of undefined” error and make your automation more robust.