Troubleshooting ADB: “Unable to open sync connection!” Error on Android Devices

Troubleshooting ADB: "Unable to open sync connection!" Error on Android Devices

22 April 2024 Stephan Petzl Leave a comment Tech-Help

Developing Android applications can sometimes come with its share of challenges, particularly when dealing with connectivity issues between your development environment and your testing device. A common issue faced by developers is the "Unable to open sync connection!" error that occurs when attempting to run or debug an Android application from an IDE like Eclipse.

This error can be particularly frustrating because it interrupts the deployment of your application to the device, hindering the development and testing process.

Possible Causes and Solutions

Let’s explore a few methods to resolve this problem so you can get back to building and testing your app efficiently.

Toggle USB Debugging

One of the most effective solutions is to toggle the USB debugging option on your device:

  1. Go to Settings on your Android device.
  2. Scroll down to Developer options.
  3. Toggle USB debugging off and then back on.

This method refreshes the connection and is often enough to resolve the issue without further action.

Reconnect the USB Cable

If toggling USB debugging doesn’t solve the problem, try disconnecting and then reconnecting the USB cable from your device to the computer. This can also reset the connection and may resolve the issue.

Restart the ADB Server

Restarting the ADB server is another common troubleshooting step:

  1. Open a terminal or command prompt on your computer.
  2. Execute the command adb kill-server to stop the ADB server.
  3. Execute the command adb start-server to restart the ADB server.

Restart the Device

In some cases, simply restarting your Android device can clear up the issue. A restart can close any lingering processes that may be interfering with the ADB connection.

Check the USB Connection

Ensure that your device is connected directly to the computer’s USB port rather than through a USB hub. Some hubs may not provide a stable connection for ADB.

Kill Background Processes and Services

Excessive background processes on your device may sometimes lead to this error. Try closing all running apps and background services. You may need to restart your IDE after doing so to see if the fix has taken effect.

Introducing Repeato

While the above steps can help solve the immediate connection issues, it’s also essential to have robust tools for testing your Android applications. This is where Repeato comes into play.

Repeato is a No-code test automation tool for iOS and Android that can streamline your testing process. With its fast editing and running of tests, Repeato can help you quickly verify fixes for issues like the “Unable to open sync connection!” error. The tool’s use of computer vision and AI allows it to work seamlessly with various app frameworks such as React Native, Flutter, and Unity.

Additionally, Repeato comes with ADB on board, enabling the execution of ADB commands via script steps, thus providing a more integrated and automated testing environment. For more information on managing ADB connections and troubleshooting related issues, you can reference our articles:

For developers looking to optimize their testing workflow, Repeato offers a practical solution to ensure that your app is functioning correctly on every release.


Dealing with ADB connection issues can be a hassle, but with the right approach, they can be resolved quickly. By following the troubleshooting steps outlined above, you can minimize downtime and keep your development process moving smoothly. And with tools like Repeato, you can further enhance your testing capabilities, making your overall development lifecycle more efficient.

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