`adb shell input` returns `Killed` response without any input registered

Question

I am trying to simulate touches on my Xiaomi Mi Max 2. I tried monkeyrunner but failed, so I am trying adb. However, each command is returned by Killed response and no touch/key is pressed. What does it mean?

Answer 1

I used to get this on a Xiaomi device with MIUI we used for development.

When sending input commands using adb I could not see any output and the adb command completed with SIGEXIT.

When I tried to manually issue it in an adb shell (on the device), I would see a killed output.

Solved by enabling USB debugging (Security setting) (Note that this is not the standard USB debugging setting, which was already enabled) in the Developer options. This required a number of confirmation steps, and once enabled, the input commands worked.