Fix ADB Device Unauthorized Error on Android Devices

ADB is a versatile tool that can be used to perform a variety of tasks on Android devices via a Windows, Linux, macOS, or ChromeOS computer. So that your PC can access your device and control it via ADB, you need to authorize the PC on your Android phone or tablet. However, if you haven’t set up ABD drivers properly, you may encounter the ‘ADB device unauthorized’ error. In this tutorial, we’ll explore the various reasons causing the issue and fix ADB issues on Android and Windows.

You can use ADB commands to transfer files, install or uninstall apps, capture screenshots, record screens, debug and fix problems, generate system logs, enable and disable OS features, install OTA zip packages, back up data, control your device remotely, and so on. ADB might come in handy when the screen or hardware keys are unresponsive.

ADB works as a bridge between your Android device and your computer. So that it can communicate with your Android device you will need to allow the USB debugging for your Windows, Linux, or Mac computer. If you don’t do that, any ADB command that you execute either won’t work at all or throw the “adb device unauthorized” error:

adb.exe: device unauthorized. This adb server's $ADB_VENDOR_KEYS is not set
Try 'adb kill-server' if that seems wrong.
Otherwise check for a confirmation dialog on your device.

If you get the ADB not found or recognized error on Windows, macOS, or Linux, it could be due to one of the following reasons:

• Faulty USB connection
• USB debugging is not enabled on your device
• RSA key fingerprint not allowed
• USB drivers need to be updated
• Latest ADB drivers are not installed
• Auto Blocker enabled (on Samsung devices)

Fixing ADB Device Unauthorized Error

As I clarified above, the USB debugging option must be enabled on the Android device otherwise ADB will not detect it at all. If you follow the steps described below carefully, you can fix the error easily.

Steps to Enable Developer Options and USB Debugging

The developer options on Android are not meant for normal users. As their very name suggests, they are supposed to be used by developers and geeks. These options remain hidden from the Android settings menu by default but can be easily activated by enabling the Developer mode. If you have already enabled debugging on your device, you can skip this part.

1. Open the Settings app on your Android phone or tablet.
2. Look for About, About phone, or About device in the settings menu. Usually, it’s located at the end of the settings menu. If you can’t find it, tap the search box in the Settings app, type “about” and you’ll find it.
3. Now, tap on Software information.
4. On the next screen, tap Build number 7 times in a row.
5. You’ll see a toast saying, “Developer mode has been turned on“.
6. Now go back to the Settings menu and you’ll find a new item named Developer options listed there. On Android devices from Chinese OEMs, you might find it under Settings > Additional settings.
7. Open the Developer options and go to the USB debugging option. Tap the toggle button next to USB debugging and tap OK when prompted to turn it on.

Revoking ADB Authorizations on Android

Before you try to fix the ADB device unauthorized error, you should start by revoking all previous ADB device authorizations on your Android device. To remove any ADB device or computer, follow the steps given below.

1. Go to Settings> Developer options on your phone.
2. Right below the option to USB debugging option, tap Revoke USB debugging authorizations.
3. A pop-up will appear. Just tap OK to revoke ADB authorization access for all computers you authorized on your Android device in the past.

Setting up ADB on Windows, Mac, & Linux

Now that you have turned on the Developer options and enabled USB debugging on your Android phone or tablet, ADB can detect it when connected via USB to a Windows, Linux, or Mac computer. However, you won’t be able to send or execute ADB commands from your PC unless you authorize the ADB command on your device.

To authorize ADB, connect your device to your computer and execute a command. To do so, you’ll have to set up ADB and Fastboot drivers first. Depending on your computer OS, the method to install and set up ADB may differ. We already have a detailed tutorial on setting up ADB and Fastboot on Windows, macOS, and Linux.

• Installing ADB and Fastboot on Windows 10 and 11
• Steps to Set up ADB and Fastboot on macOS
• Guide to Install ADB and Fastboot on Linux

Authorizing ADB Devices on Android

Well, having enabled the USB debugging on your phone and set up the ADB drivers on your computer, let’s move to the final action.

1. Open Settings > Display, and increase the screen timeout to 10 minutes. Ensure your phone’s screen is not locked while you issue the ADB command on your PC.
2. Connect your Android phone or tablet to your computer using a USB cable.
3. Navigate to the platform-tools folder and open it.
4. Now, launch a Command Prompt or PowerShell window with the folder path. That means you have to open the Command Prompt inside the folder window. There are 2 quick ways to do that.
   1. Place the mouse pointer inside the platform-tools folder window, right-click in any space, and select the “Open PowerShell window here” (Windows 10), or  “Open in Terminal” (Windows 11) option from the Windows Context Menu.
   2. Type “cmd” or “powershell” in the folder window address bar and press Enter.
5. If you’ve done it correctly you’ll see the path of the platform-tools folder in the Command Prompt window as shown below.
6. Now, unlock your phone’s screen, type the following ADB command in the Command Prompt window, and hit Enter.

   adb devices

7. When you press the Enter key, you’ll see a notification pop-up on your Android device saying, “Allow USB debugging?“. If you want to add your Windows PC to the list of authorized ADB devices for your Android phone, select the Always allow from this computer option and tap on Allow.
8. As soon as you select Allow on your phone, you’ll see your device under the List of devices attached in the Command Prompt window. Remember, ADB doesn’t show your device by its name or model number but by device ID or serial number which consists of a string of alphanumeric values.
9. In case you fail to Allow USB debugging on your phone’s screen, you will get the unauthorized device error in the command window.

   

Disabling ADB Authorization Timeout in Android

Please note that even when you select the “Always allow from this computer” option while authorizing ADB, your device will remember your computer only for 7 days. If you try to use ADB commands from the same computer after that period, you’ll have to authorize it again. To give your computer permanent authorization on your Android devices for ADB-related tasks, follow the steps below.

1. Navigate to Settings> Developer options on your Android phone or tablet.
2. In the Debugging section of the Developer options menu, you will find an option called Disable ADB Authorization Timeout. Just tap the toggle button next to this option and your device will save your PC as an authorized ADB device and remember its RSA key fingerprint in the future.

That’s all for now! I hope this detailed tutorial helped you fix the ADB device unauthorized error on Android devices.

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