Troubleshooting WebDriverException: An unknown server-side error occurred

Troubleshooting WebDriverException: An unknown server-side error occurred

5 April 2024 Stephan Petzl Leave a comment Tech-Help

Encountering a WebDriverException with an error message indicating a server-side error and a socket hang-up can be a daunting experience for any software tester. This issue is commonly associated with Appium and Android automation testing. In this guide, we will walk you through some practical steps to resolve this error and get your automated tests back on track.

Step 1: Uninstall UIAutomator2 Server Components

The error might be due to outdated or corrupted instances of UIAutomator2 server components on your device or emulator. To rectify this, you will need to uninstall these components before restarting the Appium server. Here are the commands to execute in your terminal:

      adb uninstall io.appium.uiautomator2.server
      adb uninstall io.appium.uiautomator2.server.test

After running these commands, restart the Appium server and execute your test scripts again.

Step 2: Restart Your Android Emulator or Device

If the above solution does not work, a simple restart of your Android emulator or device can sometimes resolve the issue. This step can refresh the system’s state and clear any temporary glitches that may be causing the error.

Step 3: Check for Multiple Driver Instances

Another common cause of this error is the initialization of multiple driver instances within your test suite. Ensure that you are only creating a single instance of the driver for your testing session. Here’s an example of how you should initialize your driver:

      URL url = new URL("Your Appium Server URL");
      driver = new AndroidDriver(url, capabilities);

Verify that this initialization is only happening once throughout your test suite.

Additional Tips

  • Ensure that your Appium server version is compatible with the client library you are using.
  • Check that your test device or emulator has sufficient resources and is not being overloaded with processes.
  • Review the Appium server logs for additional clues that might point to the root cause of the error.


The “socket hang up” error can be a frustrating obstacle, but by following the steps outlined in this guide, you should be able to overcome it and continue with your automated testing. Always ensure that your testing environment is clean and that you are working with the latest versions of your testing tools. If problems persist, consider seeking further assistance from community forums or professional support channels.

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