BROWSERSTACK_FAILED_TO_START_BROWSER

This document guides you with the steps to resolve the BROWSERSTACK_FAILED_TO_START_BROWSER error.

This error occurs when BrowserStack is unable to launch the browser specified in your script, thus preventing test execution.

Following are the various causes and possible fixes to the error:

Incompatible Selenium JAR or Appium version

If the target browser is incompatible with Selenium JAR or Appium version you have specified in the script, the browser will fail to launch.

You can resolve this error in the following ways:

• If your test does not require a specific Selenium JAR version or Appium version, do not set the browserstack.selenium_version, or browserstack.appium_version capability in your test. BrowserStack automatically runs your test on the most compatible Selenium JAR or Appium version for the target browser.
• If your test requires a specific Selenium JAR or Appium version, refer to the Automate capabilities generator to get a list of compatible versions for your target browser.

Incompatible browser driver

If your target browser is incompatible with the specified browser driver, the browser will fail to launch.

You can resolve this error in the following ways:

• If your test does not require a specific driver version, do not set the browserstack.chrome.driver, browserstack.firefox.driver, or browserstack.ie.driver capability. BrowserStack automatically picks the most compatible driver for your target browser.
• If your test requires a specific driver version, refer to the Automate capabilities generator to get a list of compatible driver versions for your target browser.

Invalid ChromeOptions or firefoxOptions

If you pass an incorrect or unsupported option in ChromeOptions or firefoxOptions, the browser will fail to launch.

You can resolve this error in the following ways:

• If your test does not require ChromeOptions or firefoxOptions, do not set it in your test script
• If you must use ChromeOptions or firefoxOptions, make sure the capability that you are passing is valid

Capabilities that attempt to access restricted machine/device sections are blocked for security reasons. However, if your test cases require the use of such capabilities, contact our Support team.

Faulty Chrome extension or Firefox plugin

If your test adds a faulty or corrupted Chrome extension or Firefox plugin to the remote browser, the browser may crash.

You can resolve this error in the following ways:

• If your test does not require a Chrome extension or Firefox plugin, do not pass it in your test.
• Check whether the extension you are passing is corrupted. Refer to our article on how to correctly pass plugins/extensions in a Selenium test.

Incorrect architecture (32-bit or 64-bit) for Internet Explorer Driver

If you are using Internet Explorer with Windows 8.1, Windows 8, Windows 7, or Windows XP, you can specify the IE Driver architecture (32-bit or 64-bit). However, if the OS is incompatible with the IE Driver architecture (for instance, 64-bit IE on Windows XP), the browser will fail to launch.

You can resolve this error in the following ways:

• If your test does not require a specific IE Driver architecture (32-bit or 64-bit), do not set the browserstack.ie.arch capability
• Refer to the Automate capabilities generator to find and use the compatible IE Driver architecture for the target operating system

Other causes

Since there are multiple components involved in running a test, it could be difficult to pinpoint the exact cause of the error. The browser may fail to launch due to bugs in the Selenium JAR or Appium version, browser drivers, and so on.

If the tips listed above didn’t help, try simply re-running the tests. You can also use the BrowserStack REST API to fetch session status and add a retry after every occurrence of an error.

If you consistently experience the BROWSERSTACK_FAILED_TO_START_BROWSER error, please get in touch with our Support team and share the session IDs of some failed tests so we can work on resolving the error.