MOBILE, VISUALIZATION

Fixing adb pair protocol fault Undefined error 0 on macOS (Wireless Debugging)

Overview

Fixing adb pair “protocol fault … Undefined error: 0” on macOS (Wireless Debugging)

While setting up Android Wireless Debugging on my Mac, I ran into this pairing failure:

platform-tools % adb pair 192.168.0.38:39019
Enter pairing code: 788790
error: protocol fault (couldn't read status message): Undefined error: 0

At first glance this looks like an ADB or device-side issue, but on macOS the cause can be much simpler: Local Network permission.

Why it happens

Wireless Debugging uses your local network to communicate with the Android device. If macOS blocks the app that initiated the connection (often Android Studio, or sometimes the terminal process depending on how you launched things), ADB may fail in a confusing way, including the “protocol fault” / “Undefined error: 0” message.

The fix (macOS Local Network permission)

  1. Open System Settings (or System Preferences on older macOS).
  2. Go to Privacy & Security.
  3. Find Local Network.
  4. Enable access for Android Studio (and any related tools if listed).

After allowing Local Network access, retry:

adb pair <device-ip>:<pairing-port>

In my case, pairing succeeded immediately after toggling that permission.

Reference

I found the key hint from this Stack Overflow thread:

https://stackoverflow.com/questions/36951897/wireless-usb-debugging-for-android-studio-in-mac

updated_at 22-02-2026