Hi! Maxime Devos skribis: > FWIW, the following works as expected (no error message), using the store path in .policy: > $ pkexec /gnu/store/zk4kb4437032swahywmgyzn55b5w5wj8-mate-power-manager-1.24.2/sbin/mate-power-backlight-helper --set-brightness=300 > Maybe MATE is trying the equivalent of "pkexec /wrong/store/path/mate-power-backlight-helper --etcetera" instead > of referring to the action by name org.mate.power.backlight-helper. > > Note the store path is different. Now try something different > > $ which mate-power-backlight-helper >> /run/current-system/profile/sbin/mate-power-backlight-helper > $ ls -l /run/current-system/profile/sbin/mate-power-backlight-helper >> /gnu/store/ffqhy4xdpzkg06rlq76zrbwn8v3rqgw9-mate-1.24.1/sbin/mate-power-backlight-helper These are different versions (1.24.2 vs. 1.24.1). But that’s just two store file names; where’s the third one? Isn’t the problem that you reconfigured and so there’s now a mismatch between the polkit rule in effect, which expects 1.24.1 (say), and the version you’re running? (FWIW brightness change works in GNOME.) Thanks, Ludo’.