Autopilot doesnt read sd card

hi

there is a pixhawk 6c autopilot. we have nearly 5 flights with n problem. after that, the autopilot started to give error messages continiously like disarming randomly, logging failed … rebooting the copter by itself, and then not writing and reading the log files on the sd card. we tried new sd card and nothing changed. with no sd card in the autopilot, the copter flies normally. but ii want flight logs.