How can I boot to a specific partition with ADB? If I have ADB access to device, how can I specify the boot partition and reboot. I tried with setprop but this failed,
#&gt; setprop ro.boot.slot_suffix _b
libc: Unable to set property &quot;ro.boot.slot_suffix&quot; to &quot;_b&quot;: error code: 0xb
setprop: failed to set property 'ro.boot.slot_suffix' to '_b'
Using bootctl
Though it requires adb root, one method to do this would be to use bootctl if available.
#&gt; bootctl set-active-boot-slot SLOT
#&gt; reboot

Note: SLOT is a number, you can find out the labels by looping through them and calling get-suffix for example this little shell script,
for slot in $(seq 0 $(expr $(bootctl get-number-slots) - 1)); do
  echo $slot: $(bootctl get-suffix $slot);
done;

Which will return the mapping,
0: _a
1: _b

See also: How can I tell whether I am booted into the A or B partition?