fastboot commands

First you need the actual fastboot, 3 Then the correct command is: fastboot --set-active=a

I guess your bootloader is unlocked? Did you try to change the active slot? Get the current active boot slot: fastboot getvar current-slot

fastboot getvar currentslot Xiaomi Mi A2$ fastboot getvar current-slot current-slot: a finished total time: mf@mf-OptiPlex-3040:~PulpitXiaomi Mi A2$ fastboot

fastboot set active slot I guess your bootloader is unlocked? Did you try to change the active slot? Get the current active boot slot: fastboot getvar current-slot