Samsung Auto Blocker blocks USB debugging: how to fix it
On recent Samsung Galaxy phones, Auto Blocker blocks commands sent over a USB cable, which is exactly what ADB sends. If the phone connects but nothing happens and the "Allow USB debugging?" prompt never appears, switch Auto Blocker off while you work.
Symptoms
- The computer sees the phone but commands do nothing.
- The "Allow USB debugging?" prompt never appears.
- USB debugging is on and the cable is a data cable, yet the connection fails.
Fix
- Open Settings > Security and privacy > Auto Blocker.
- Switch Auto Blocker off, or turn off its option to block commands and software updates by USB cable.
- Unplug and replug the cable, unlock the screen and press Connect phone in the slimdroid tool.
- Tap Allow on the "Allow USB debugging?" prompt.
Put it back afterwards
Auto Blocker exists to stop USB attacks, so it should end up on. Samsung turns it back on by itself after about 30 minutes; keep that automatic re-enable switched on rather than disabling it for good. It is your safety net if you forget. If commands stop working partway through a session, it has re-armed: switch it off again and reconnect. Also switch USB debugging off and revoke authorizations when you finish; enable USB debugging covers the whole cycle.
Is turning Auto Blocker off dangerous?
It lowers a protection while it is off. Keep the phone locked while connected, use your own cable and computer, and leave Samsung's automatic re-arm (about 30 minutes) switched on so it protects you again even if you forget.