Common ADB Problems and How to Fix Them

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Last Updated: September 2, 2026

Android Debug Bridge (ADB) is powerful, but it’s not immune to connection issues, driver problems, and authorization errors. This guide walks through the most common ADB problems and their solutions, tested across Windows, Mac, and Linux.

Android smartphone with developer options and USB debugging enabled
Developer options and USB debugging are the gateway to ADB connectivity

Quick Diagnostics

Before diving into specific fixes, run these diagnostic commands:

# Check ADB version
adb version

# List connected devices
adb devices

# Check ADB server status
adb get-state

If adb devices returns an empty list or shows your device as “unauthorized” or “offline,” you’ve got work to do.

Problem 1: Device Shows as “Unauthorized”

Symptoms

$ adb devices
List of devices attached
ABC123456789    unauthorized

Root Cause

Your computer’s RSA key wasn’t authorized on the Android device. This happens when:

  • First-time ADB connection
  • USB debugging was disabled and re-enabled
  • Developer options were reset
  • RSA keys were revoked on the device

💡 Pro Tip: Always check “Always allow from this computer” when the RSA prompt appears. This prevents repeated authorization requests.

Solution A: Accept RSA Prompt on Device

  1. Disconnect and reconnect the USB cable
  2. Check your Android device screen for “Allow USB debugging?” prompt
  3. Check “Always allow from this computer”
  4. Tap “Allow”

If the prompt doesn’t appear, continue to Solution B.

Solution B: Revoke and Re-authorize

On your Android device:

  • Go to Settings → Developer Options
  • Tap “Revoke USB debugging authorizations”
  • Confirm revocation

On your computer:

adb kill-server
adb start-server
adb devices

Check your device screen again for the RSA prompt.

Solution C: Clear RSA Keys Manually

On Windows:

del %USERPROFILE%\.android\adbkey
del %USERPROFILE%\.android\adbkey.pub
adb kill-server
adb start-server

On Mac/Linux:

rm ~/.android/adbkey
rm ~/.android/adbkey.pub
adb kill-server
adb start-server

After deleting the keys, reconnect your device and authorize the new prompt.

USB cable connecting smartphone to laptop for debugging
A quality USB cable and direct connection are essential for reliable ADB communication

Problem 2: Device Not Detected

Symptoms

$ adb devices
List of devices attached
# (empty list)

Solution A: Enable USB Debugging

USB debugging must be enabled for ADB to work:

  1. Go to Settings → About phone
  2. Tap “Build number” 7 times to enable Developer Options
  3. Go to Settings → Developer Options
  4. Enable “USB debugging”
  5. If available, also enable “USB debugging (Security settings)”

Solution B: Check USB Connection Mode

Android devices can connect in different modes. ADB requires specific modes:

  1. Pull down notification shade when connected
  2. Tap “USB charging this device” or similar notification
  3. Select “File Transfer” (MTP) or “PTP” mode
  4. Avoid “Charging only” mode — ADB won’t work

Some devices work better with PTP mode for ADB connections.

Solution C: Try Different USB Cable/Port

  • Use the original cable that came with your phone
  • Avoid USB hubs — connect directly to computer
  • Try different USB ports (USB 3.0 vs 2.0)
  • Avoid damaged or cheap cables — they may only support charging

⚠️ Warning: Cheap USB cables are a leading cause of ADB connection issues. They often only have power wires and lack data lines entirely.

Terminal window showing command line interface
Terminal commands are your primary diagnostic tool for ADB issues

Problem 3: Wireless ADB Won’t Connect

Symptoms

$ adb connect 192.168.1.100:5555
failed to connect to 192.168.1.100:5555

Solution A: Enable Wireless Debugging (Android 11+)

Modern method (no USB cable needed on Android 11+):

  1. Go to Settings → Developer Options → Wireless debugging
  2. Tap “Wireless debugging” to enable
  3. Note the IP address and port (e.g., 192.168.1.100:37847)
  4. On computer: adb pair <IP>:<PAIR_PORT> (use pairing code from phone)
  5. Then: adb connect <IP>:<PORT>

Solution B: Enable via USB First (Android 10 and below)

# Connect device via USB first
adb tcpip 5555

# Find device IP
adb shell ip addr show wlan0

# Connect wirelessly
adb connect 192.168.1.100:5555

# Verify connection
adb devices
Software developer debugging code on computer screen
Systematic debugging is the key to solving persistent ADB issues

Summary

Problem Quick Fix
Unauthorized Revoke authorizations, restart ADB, accept prompt
Not detected Enable USB debugging, check cable/mode
Wireless won’t connect Same network, use USB first for setup
Version conflict Remove duplicate ADB installations
Daemon not running Kill ADB, check port 5037

Most ADB issues fall into these categories and resolve with the solutions above. When in doubt, restart everything: ADB server, device, and even your computer.

Related Guides:

Last updated: September 2, 2026

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