Test on Real Devices

Learn about the NoAlertPresentException in Selenium. User BrowserStack Automate to test on real device cloud.

Get Started free
Home Guide Understanding NoAlertPresentException in Selenium

Understanding NoAlertPresentException in Selenium

By Siddharth Murugan, Community Contributor - December 13, 2024

When working with Selenium, handling browser alerts is a common task. However, errors like the NoAlertPresentException can arise when the script attempts to interact with an alert that doesn’t exist or has already been dismissed.

This article will explore what the NoAlertPresentException is, why it occurs, and how to effectively handle it to ensure smooth test execution.

Table of Contents

What are Alerts and Exception?

Before understanding the noAlertPresentException Error in Selenium, you should understand what an alert means.

An alert in a web browser is a type of pop-up dialog box that typically displays a message to the user, often with a button for acknowledgment or action. Next, you should understand the term Exception. An exception in programming means an event that disrupts the normal flow of a program’s instructions.

This kind of exception arises when there is no proper code that cannot handle the error directly.

NoAlertPresentException is an exception that occurs in Selenium – a web automation framework. This generally occurs when the script tries to interact with the alert present in the browser, is either not prese,nt or has already been closed in the browser.

alert

Also Read: What is the Difference between an Alert and a Popup?

What is NoAlertPresentException in Selenium?

Exceptions are often used to manage errors, unexpected conditions, or events that may occur during the program’s runtime. NoAlertPresentException is thrown when an operation trying to interact with an alert (such as accepting or dismissing an alert) is performed, is either not present, or has already been closed in the browser.

For example, if you try to interact with an alert using methods like accept(), when no alert exists, Selenium will raise a NoAlertPresentException.

For demo purpose, you can use this website for testing: https://www.bstackdemo.com/

from selenium import webdriver

from selenium.webdriver.common.by import By

# Initialize the WebDriver

driver = webdriver.Chrome()



#Opening the web page of selenium

driver.get("https://www.bstackdemo.com/")



#Waiting for the web page to load

driver.implicitly_wait(10)




# Try to find an element

element = driver.find_element(By.ID,”alert”)



# Attempting to accept an alert (but no alert is present)

driver.switch_to.alert.accept()



#Quitting the session

driver.quit()

error message

If you execute the above piece of code, you will get the exception saying `NoAlertPresentException

selenium.common.exceptions.NoAlertPresentException: Message: no such alert

When Does NoAlertPresentException Occur?

NoAlertPresentException occurs due to the following reasons:

  • Alert doesn’t exist: The most common scenario is when your script tries to switch focus to an alert that hasn’t appeared or has already been closed.

For example:

alert = driver.switch_to.alert

            alert.accept()

Selenium will raise a NoAlertPresentException if there is no alert present when these lines are executed.

  • Timing Issues: Automation scripts often execute faster than the application’s response time. The exception will be thrown if your script attempts to interact with an alert before it fully appears. This can happen in dynamic web applications where alerts are triggered based on user actions or asynchronous events.
  • Alert closed already: If an alert was present but got closed unexpectedly (either manually by a user or programmatically by the application) before the script could interact with it, any subsequent attempt to interact will result in the exception.
  • Multiple alerts: Also known as nested alerts require careful handling. For example, the first alert might ask, Are you sure you want to subscribe to the newsletter? with Yes/No options, followed by another alert prompting for an email ID. Interacting with alerts out of sequence can lead to a NoAlertPresentException.

Read More: How to handle Alerts & Popups in Selenium

How to Handle NoAlertPresentException in Selenium

Below are ways in which you can handle NoAlertPresentException in Selenium:

  • The most common cause of NoAlertPresentException is trying to interact with an alert before it appears. To avoid this, use an explicit wait to wait for the alert to be present.
  • Check if an alert is present before attempting to interact with it. This is especially useful when alerts may or may not appear based on application behavior.
  • In cases where the alert appears unpredictably, you can use retry logic to check for the alert multiple times within a loop.
  • Sometimes, assuming the alert will appear without verifying the application’s state can cause issues. For example, if an alert is expected after a button click, ensure the button click action is successful before checking for the alert.
  • If NoAlertPresentException persists, use debugging techniques to confirm that the alert appears as expected in the application workflow. Sometimes, delays or conditional logic in the application can make alerts appear inconsistently.

Steps to Fix NoAlertPresentException in Selenium

Below are the steps on how to fix NoAlertPresentException in Selenium:

  • Using explicit wait: One way to overcome this exception is by adding explicit wait. Adding this explicit wait will make the code wait until the alert is present like below,
from selenium.webdriver.support.ui import WebDriverWait

from selenium.webdriver.support import expected_conditions as EC

from selenium.common.exceptions import TimeoutException

from selenium import webdriver



# Initialize the WebDriver

driver = webdriver.Chrome()



driver.get("https://www.bstackdemo.com/")



try:

    #waiting till the alert is present

    WebDriverWait(driver, 10).until(EC.alert_is_present())

    alert = driver.switch_to.alert

    alert.accept()

except TimeoutException:

    print("No alert appeared within the given time.")

#Quitting the session

driver.quit()

After executing above code, you will notice that error is handled by the exception

exception 1

  • Verifying the presence of the alert: The next way of handling this error is by checking whether the alert is present on the screen like the below piece of code,
from selenium.common.exceptions import NoAlertPresentException

from selenium import webdriver

# Initialize the WebDriver

driver = webdriver.Chrome()



driver.get("https://www.bstackdemo.com/")



#Function to verify the presence of an alert

def is_alert_present(driver):

    try:

        driver.switch_to.alert

        return True

    except NoAlertPresentException:

        return False



#Calling the function

is_alert_present(driver)



#Clicking the alert if it is present

if is_alert_present(driver):

    alert = driver.switch_to.alert

    alert.accept()

else:

    print("No alert to handle.")

#Quitting the session

driver.quit()

After executing the above code, you will notice that the error is handled by the exception,

exception 2

  • Retry logic: In situations where alerts appear occasionally, implementing a retry mechanism can help handle intermittent alerts.
import time

from selenium.common.exceptions import NoAlertPresentException

From selenium import webdriver

# Initialize the WebDriver

driver = webdriver.Chrome()



driver.get("https://www.bstackdemo.com/")

for attempt in range(5):

    try:

        alert = driver.switch_to.alert

        alert.accept()

        break

    except NoAlertPresentException:

        time.sleep(1)

else:

    print("Failed to find alert after multiple attempts.")

#Quitting the session

driver.quit()

After executing above code, you will notice that error is handled by the exception,

exception 3

Why is Testing on Real Devices and Browsers Important?

Testing on emulators and simulators can be cost-effective. Nevertheless, testing web applications on real devices is crucial as testing on simulators and emulators cannot represent real-world scenarios such as network conditions, hardware configurations, and environmental factors.

BrowserStack is a popular cloud-based platform with 3,500+ real devices and browsers for testing different devices, browsers, and OS combinations. It offers a pool of products, such as Automate, Live, Percy, App Live, and App Automate, to cater to different types of testing.

BrowserStack Automate Banner

Below are some of the features provided by BrowserStack’s Automate product:

  • Diverse environment testing: With BrowserStack, you can automate with multiple frameworks, such as Selenium, Playwright, Puppeteer, Cypress, etc., and test across different devices, operating systems, and browsers.
  • Real Devices and Browsers: Testing the application on real devices and browsers to simulate real user conditions is always wiser. Testing on real devices gives actual confidence about the application’s performance.
  • Concurrent test execution: Multiple Selenium tests can be executed simultaneously, reducing the total execution time, giving quicker feedback, and accelerating deployment cycles.
  • Custom Reports with Artifacts: In Automate, custom reports can be generated to provide detailed and customized reports for automated test execution.
  • Easy Integration with CI/CD Pipeline: BrowserStack’s Automate product can be seamlessly integrated with popular CI/CD tools such as Jenkins, TeamCity, TravisCI

Why Use BrowserStack Automate for Selenium Tests?

Different devices and browsers render web pages differently. Testing an application in real devices and browsers with a real environment setup is advisable to ensure that it behaves uniformly across different pools of devices and browsers.

Talk to an Expert

BrowserStack Automate offers a real device cloud platform where you can access over 3500+ different devices, browsers, and OS combinations using this platform.

Testing on real devices and browsers ensures a high-quality user experience and compatibility across different platforms and validates the application’s performance and security in real user conditions.

Conclusion

The NoAlertPresentException is a useful indicator that your automation script is attempting to interact with an alert that isn’t currently available. By incorporating proper wait strategies, verifying the presence of alerts before interacting, and handling exceptions gracefully, you can make your Selenium tests more reliable and resilient to such issues.

Useful Resources for Selenium

Methods, Classes, and Commands

Configuration

XPath

Locators and Selectors

Waits in Selenium

Frameworks in Selenium

Miscellaneous

Best Practices, Tips and Tricks

Design Patterns in Selenium: Page Object Model and Page Factory

Action Class

TestNG and Selenium

JUnit and Selenium

Use Cases

Types of Testing with Selenium

Tags
Automation Testing Selenium

Featured Articles

Top Selenium Commands for Developers and Testers

How to handle Alerts and Popups in Selenium?

Automation Tests on Real Devices & Browsers

Seamlessly Run Automation Tests on 3500+ real Devices & Browsers