Sometimes, the FDM Web UI stops responding. I’ve found this especially on 6.5 code. To restart tomcat, go into expert mode and disable/enable:
> expert
admin@fp:~$ sudo su -
Password:
root@fp:~# cd /ngfw/var/cisco/ngfwWebUi/
## delete this file if it exists
root@fp:ngfwWebUi# rm .bootstrap-failed
root@fp:ngfwWebUi# pmtool disablebyid tomcat
root@fp:ngfwWebUi# pmtool enablebyid tomcat
The web service takes a while (10+ minutes) to come back online.
h/t to Pieter-Jan Nefkens at https://www.nefkens.net/fdm-application-fails-after-upgrade/