A common and reliable pattern in service unit files is thus:
NoNewPrivileges=yes
PrivateTmp=yes
PrivateDevices=yes
DevicePolicy=closed
ProtectSystem=strict
Recently started working on policy migration to a new system. The following errors are cryptic and it took some digging to figure out what was going on. I saw others online had the same errors but the general fix seemed to be "load the new policy". But didn't really go into details of how policies are fixed.
Compiling targeted netmgr module
Creating targeted netmgr.pp policy package
Loading targeted modules: netmgr
Failed to resolve filecon statement at /var/lib/selinux/targeted/tmp/modules/400/netmgr/cil:50
/usr/sbin/semodule: Failed!
make: *** [/usr/share/selinux/devel/include/Makefile:145: reload] Error 1
Cause: fc file contains a type that it can't resolve. So using: