@Clément Dumont
The "/var/run/knox" is mounted as tmpfs so it might be deleted by the operating system after host reboot. So if you find this issue in OS like RHEL7 then please try changing the "knox PID" to some other path.
Ambari UI --> Knox --> Configs --> Advanced --> "Advanced knox-env" --> "Knox PID dir"<br>
The "Knox PID dir" by default has a value "/var/run/knox" you can change it to something else.
Red Hat Enterprise Linux 7, the/rundirectory is a temporary file storage system (tmpfs) that bind mounts the/var/rundirectory.
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/migration_planning_gui...
