Have you enabled USB debugging in the developer settings, connected your smartphone to the computer, but Android Studio, ADB or other tools stubbornly do not see the device? Or an error device unauthorized, no devices foundappears, and the Windows Device Manager displays unknown hardware with a yellow triangle?

The problem with USB debugging is one of the most common among developers, testers and users who are trying to obtain root-rights, flash custom software or simply transfer data via ADB. The reasons may lie in the smartphone settings (for example, reset permissions after an update), or in PC drivers, a damaged cable, or even manufacturer hardware limitations. In this article we will analyze all possible scenarios of non-working USB debuggingincluding rare cases when the problem lies in the firmware or bootloader lock.

Important: if you have never enabled Developer mode, first check whether the option itself is activated. To do this, go to Settings → About phone → Build number and tap on it 7 times. After this, the item For developers.

1 will appear in the main settings menu. Checking the basic conditions: cable, port and power supply

Before digging deep into the settings Android or reinstalling drivers, rule out the simplest reasons. According to statistics, 30% of problems with USB debugging are associated with physical factors:

  • 🔌 Cable: use an original cable from a smartphone or a certified one USB Type-C with support for data transfer (not all charging cables are suitable for ADB). Cheap Chinese wires often have only two contacts for power, without data lines.
  • 🖥️ USB port on PC: try connecting to another port (preferably USB 2.0 - it works more stable with ADBthan USB 3.0/3.1). Avoid hubs and extenders.
  • 🔋 Power source: If the smartphone is discharged below 15%, some devices block USB debugging to save energy. Connect the charger.
  • 📱 Connection mode: When a notification about the type of USB connection appears, select File transfer (MTP) or Photo transfer (PTP) — Charging only disables data transfer.

If you use Mac or Linux, check if the power management system is blocking the USB port. On Windows disable the power saving mode for USB controllers in the device manager.

📊 What cable are you using to connect?
Original from a smartphone
Certified USB-C
Cheap uncertified
I don’t know

2. Developer settings: what could go wrong

Even if you enabled USB debugging in the menu For developers, this does not guarantee its functionality. Here are typical errors in the settings:

  • 🔄 Reset permissions: After updating Android or resetting the settings, all previously granted permissions for ADB are canceled. A window with a request should appear on the smartphone screen Allow USB debugging? —if it is not there, then the connection is not established.
  • 🔒 OEM blocking: on some devices (for example, Samsung, Xiaomi, OnePlus) this is additionally required enable OEM unlocking in the developer menu. Without this ADB will be limited.
  • 🛡️ MIUI/EMUI/One UI: proprietary shells may hide the debugging request or require confirmation via Mi Account (Xiaomi), Huawei ID or Samsung Account.
  • ⚙️ Default mode: in some firmware (for example, ColorOS on Oppo/Realme), by default debugging only works in Charge onlymode. Try switching the USB mode manually.

To reset all permissions ADBexecute in the command line:

adb kill-server

adb start-server

Then disconnect and connect again smartphone - a window asking for permission should appear.

☑️ Checking developer settings

Completed: 0 / 4

3. Problems with drivers on a PC: how to install the correct ones

On Windows the absence or incorrect operation of drivers is the most common reason why USB debugging does not work. Even if the device manager shows Android Device, this does not mean that the driver supports ADB.

First check if the device is detected in the manager:

  1. Connect your smartphone to the PC.
  2. Open Device Manager (Win + X → Device Manager).
  3. Look in the sections Portable devices, Other devices or USB controllers.

If you see a yellow triangle or an inscription ADB Interface with an exclamation mark, the driver is installed incorrectly.

Solutions:

  • 🖥️ Universal Driver: download Google USB Driver (official package from Android SDK). Suitable for most clean devices as Android.
  • 📱 Driver from the manufacturer: For Samsung, Xiaomi, Huawei and other brands, download drivers from their official websites (for example, Samsung USB Driver for Mobile Phones).
  • 🔧 Manual installation: if the device is defined as Android ADB Interface, but with an error, update the driver manually by specifying the path to the folder with Google USB Driver.
  • 🚫 Driver conflict: remove all previously installed drivers for Android via Removing the device in the manager, then reconnect the smartphone.

For Mac and Linux drivers are usually not required, but you may need to configure rules udev (for Linux). Example rule for ADB:

SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0666", GROUP="plugdev"

Where 18d1 — Vendor ID for Google (you can find out yours with the command lsusb).

💡

If after installing the drivers ADB still does not see the device, try connecting via Wi-Fi: adb tcpip 5555, then adb connect IP_device:5555.

4. Problems with ADB: restart, version and conflicts

The tool itself ADB (Android Debug Bridge) may not work correctly due to outdated version, conflicts with other apps or damaged files. Here's what to check:

  • 🔄 ADB Version: if you use Android Studio, update SDK Platform-Tools via SDK ManagerFor a separate installation, download the latest version from official website.
  • 🛠️ Port conflict: some apps (for example, Genymotion, BlueStacks) occupy the port 5037, which is used ADB. Check whether the port is occupied. command netstat -ano | findstr 5037 and terminate the conflicting process.
  • 🗑️ ADB cache: clear the cache with the command adb kill-server, then restart the server adb start-server.
  • 🔍 ADB logs: run ADB in debug mode: adb -d shell setprop log.tag.ADB DEBUG, then look at the logs through adb logcat.

If you connect several devices, specify the target explicitly:

adb -s REMOTE_ID device shell

To see the list of connected devices, use:

adb devices
Symptom Possible cause Solution
device unauthorized Permission for debugging on the smartphone is not confirmed Disconnect/connect the device, confirm the request on the screen
no devices found Drivers are not installed or ADB is not running Check the drivers, restart adb server
The device is displayed as offline Version conflict ADB or firmware Update ADB and smartphone firmware
The device appears and disappears Problems with the cable or USB port Try a different cable/port, disable USB power saving
💡

If adb devices shows the device as unauthorized, but the permission request does not appear - try resetting all permissions ADB in the smartphone settings (Settings → Applications → ADB → Reset permissions).

5. Blocking at the firmware and bootloader level

On some devices (especially Samsung, Huawei, Xiaomi) USB debugging may be blocked at the firmware or bootloader level. This most often appears after:

  • Updates Android (especially on MIUI, EMUI, One UI).
  • Reset to factory settings.
  • Activation of protection functions (for example, Knox on Samsung).

How to check and fix:

  1. Check the bootloader status: run adb reboot bootloader, then fastboot oem device-info (for Samsung) or fastboot getvar all (for other devices). If Device unlocked: false, the bootloader is locked.
  2. Unlock OEM: on some devices (for example Xiaomi) you need to link your account to the device and wait 7-15 days to unlock the bootloader.
  3. Check VBMeta: system integrity check ( Android 10+ . If it works,Verified Boot) may be enabled on ADB will be limited. Look at the logs via adb logcat | grep avb.

For Samsung s Knox:

⚠️ Attention: if the device is activated Knox (check in Settings → Biometrics and security → Other security options), unlocking the bootloader will lead to irreversible activation of the flag. Knox 0x1. This will void the warranty and may block some features (for example, Samsung Pay, Secure Folder).
How to bypass ADB lock on Xiaomi without unlocking the bootloader?

On some devices Xiaomi (for example, Redmi Note 10 Pro) you can temporarily turn on USB debugging via mode EDL (Emergency Download Mode). To do this:

1. Turn off the smartphone.

2. Press Volume up + Volume down + Power on 10–15. seconds.

3. Connect to the PC - the device will be detected as Qualcomm HS-USB QDLoader 9008.

4. Use Mi Flash Tool for firmware without unlocking.

Risk: incorrect actions in the mode EDL can turn the smartphone into a "brick".

6. Alternative debugging methods: Wi-Fi, Bluetooth and third-party tools

If USB debugging persistently does not work, consider alternative connection methods:

  • 📶 ADB over Wi-Fi:
    1. Connect to USB and run adb tcpip 5555.
    2. Disconnect the cable and connect via network: adb connect IP_devices:5555.
    3. You can find out the IP in the Wi-Fi settings or by command adb shell ip route.
  • 🔵 Bluetooth ADB (Android 11+): enable in the developer menu Debugging via Bluetooth, then pair the devices and connect via adb connect BT address.
  • 🖥️ Scrcpy: this tool allows you to control your smartphone from a PC via USB or Wi-Fi, even if ADB it is unstable. Download from GitHub.
  • 🔧 TeamViewer QuickSupport: if you only need remote assistance, this application allows you to control your smartphone without ADB.

    • on ADB over Wi-Fi on Android 11+ requiring connection confirmation on the smartphone every time the network changes. On Android 10 and below, the connection is maintained until rebooted.

    💡

    If ADB over Wi-Fi works slowly, reduce the delay with the command adb shell setprop persist.adb.tcp.ackevery 0.

    7. Hardware problems and malfunctions

    If none of the software methods help, the reason may lie in the hardware:

    • 🔌 Damaged USB port: if the port is physically damaged (for example, after a fall or moisture), data transmission may be unstable. Check if the connector is wobbly when connecting the cable.
    • 🔋 USB controller: on some smartphones (especially budget ones), the USB controller fails over time. Symptoms: the device is charging, but is not recognized as a storage device or a device. USB controller: If the smartphone is not detected on any PC, the USB circuit on the board may be damaged. This requires repair at a service center. ADB-device.
    • 📱 Problems with the motherboard: If the smartphone is not detected on any PC, the USB circuit on the board may be damaged. This requires repair at a service center.
    • ⚡ Static electricity: rare, but it happens that a discharge of static electricity damages the USB controller. Try connecting through a different PC port or using an antistatic wrist strap.

      • To diagnose hardware problems:

      1. Try connecting your smartphone to another PC/laptop.
      2. Check whether the device is detected in Device Manager as Unknown device.
      3. If the smartphone is charging but does not transmit data, try using OTG cable to connect a flash drive - if the flash drive is not detected, the problem is in the port.

    On some devices (for example, Samsung Galaxy S20+) after replacement The display or battery may be blocked by protection. In this case, a reset USB debugging is required. In this case a reset is required Knox or firmware via Odine.

    FAQ: Frequently asked questions about USB debugging

    ❓ Why does ADB not see the device even though the drivers are installed?

    Possible reasons:

    • The request for debugging on the smartphone has not been confirmed (check notifications).
    • Version conflict ADB (update Platform-Tools).
    • The device is connected in mode Charging only.
    • Blocking by antivirus (for example, Avast or Kaspersky can block adb.exe).

      • Solution: restart ADB (adb kill-server && adb start-server), check the USB mode and resolution.

    ❓ How to enable USB debugging if the sensor does not work?

    If the screen does not respond to touches, but the device turns on:

    1. Connect the keyboard via USB OTG (or Bluetoothif OTG does not work).
    2. Press Win + V (if a keyboard is connected) to bring up the accessibility menu.
    3. Use the keys Tab, Enter and arrows to navigate the menu Settings → System → For developers.
    4. Enable USB debugging and connect via ADB.

    If the sensor is completely dead, all that remains is to flash the firmware via Fastboot or EDL (requires unlocking the bootloader).

    ❓ Is it possible to enable ADB without access to the settings?

    Yes, but the methods depend on the model:

    • For Samsung: use the combination Volume down + Bixby + Power to enter Download Mode, then flash TWRP via Odine.
    • For Xiaomi: enter Fastboot (Volume down + Power) and flash TWRP via fastboot flash recovery twrp.img.
    • For Pixel: use Android Flash Tool from Google to unlock the bootloader.

    ⚠️ Attention: These methods require unlocking the bootloader and can lead to data loss.

    ❓ Why did debugging stop working after updating Android?

    Updates are often reset:

    • Permissions ADB (you need to reconfirm on your smartphone).
    • Settings OEM unlocking (on Samsung, Xiaomi).
    • Drivers on PC (required reinstallation).

    Solution:

    1. Disconnect and reconnect the device.
    2. Check the menu For developers —the settings may have been reset.
    3. Update ADB and drivers.
    ❓ How to check if my smartphone supports USB debugging?

    Almost all devices on Android (starting from version 2.2 Froyo) support USB debugging, but there are exceptions:

    • Blocked bootloader: some operators (for example, Verizon, AT&T) block ADB on proprietary firmware.
    • Devices without Google Services: on Huawei without GMS (for example, Mate 40 Pro) manual installation of ADBkeys may be required.
    • Children's/corporate devices: smartphones with MDM (mobile device management) are often blocked ADB.

    To check support, connect the device to your PC and run adb devices. If the command is executed without errors, but the device is not displayed, the problem is in the settings or drivers, and not in hardware incompatibility.