@tinchus DSF services run as dsf user, so it cannot access root files unless the "other" (anonymous) flags are set accordingly. You can try out https://pkg.duet3d.com/testing/image_2022-07-28-DuetPi.zip or https://pkg.duet3d.com/testing/image_2022-07-28-DuetPi-lite.zip which feature automatic USB mount support with correct privileges using usbmount.