Device "upfgtp0" cannot created

If you encounter the error as below:

INFO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/upf_init.c:164 UpfInit() Config: /home/calee/go/src/free5gc/src/upf/build/config/upfcfg.test.yaml  UPF=Util
INFO[2020-06-06T13:45:11Z] Set log level: info                           UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/lib/gtpv1/src/gtp_link.c:27 GtpLinkCreate() GTP device named upfgtp0 Create fail  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/lib/gtpv1/src/gtp_path.c:49 GtpTunCreate() GtpLinkCreate fail  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/lib/gtpv1/src/gtp_path.c:144 GtpDevListCreate() GTPv1 tunnel create fail : IP[10.200.200.102], ifname[upfgtp0]  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/up/up_path.c:74 GTPv1ServerInit() GtpLinkListCreate Fail  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/upf_init.c:170 UpfInit() UPF - GTP-U Server error when UPF initializes  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/upf.c:28 main() UPF failed to initialize  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/up/up_path.c:233 BufferServerTerminate() epoll deregister error  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/upf_init.c:183 UpfTerm() UPF - Buffer Server error when UPF terminates  UPF=Util
ERRO[2020-06-06T13:45:11Z] /home/calee/go/src/free5gc/src/upf/src/upf.c:36 main() UPF terminate error  UPF=Util
Cannot find device "upfgtp0"

This is most of the time caused by gtp5g module not being inserted.

Please notice that this kernel module will not be automatically loaded when booting. You will need to install it manually every time when you reboot the vm/system.