[centos@ip-10-10-11-82 ~]$ vppctl set int feature help
set interface feature: parse error `help'

OK, so without help, try the obvious...

[centos@ip-10-10-11-82 ~]$ vppctl set int feature
[centos@ip-10-10-11-82 ~]$ tcpdump: pcap_loop: The interface went down

(that was a crash.)