Fix ADB Device Not Found or Unauthorized Errors

Problem overview

When typing adb devices in the command prompt or terminal, your phone does not appear in the list, or it shows up as unauthorized.

Common causes

• USB debugging is not enabled on the phone
• Missing or incorrect Windows ADB drivers
• Faulty USB cable lacking data pins (charge-only cable)
• Stale ADB server daemon running on the computer

Solution 1: Enable USB debugging and authorize

1. On your phone, go to Settings > About phone and tap Build number 7 times.
2. Go to Settings > System > Developer options.
3. Toggle on USB debugging.
4. Connect the phone to the computer.
5. Unlock your phone screen. You should see a prompt: Allow USB debugging? Check Always allow from this computer and tap Allow.

Solution 2: Restart the ADB server

1. Open your terminal or command prompt.
2. Run the following command to kill the hung background process:

   adb kill-server

3. Start it again and check for devices:

   adb start-server
   adb devices

Solution 3: Install correct Windows drivers

1. Right-click the Windows Start button and select Device Manager.
2. Look for your phone under Portable Devices or Other devices (it may have a yellow exclamation mark).
3. Right-click it and select Update driver.
4. Choose Browse my computer for drivers > Let me pick from a list of available drivers on my computer.
5. Select Android Device > Android ADB Interface.
6. Accept the warning and install the driver.

Solution: Roll back app or system updates

System glitches or app crashes following an update can be fixed by uninstalling app updates or rolling back system software.

1. Open Settings on your Android device and tap Apps (or App Management).
2. Select the malfunctioning app (e.g., Google Play Services, Camera, or System WebView).
3. Tap the three dots menu in the top-right corner and select Uninstall updates.
4. Confirm by tapping OK to restore the app to its factory version.
5. If the issue is system-wide after an OTA update, clear the System Cache Partition via Recovery Mode (power off device, then hold Power + Volume Up to enter Recovery).