After upgrading (fresh install due to middlewared service not starting) to 24.10.1 from 24.10.0.2, it seems nginx expects two files in /etc/certificates to exist.
truenas_default.crt
truenas_default.key.
I was able to get nginx to start by copying my current key/cert to these names, which allowed me to access the web ui again, however after creating a new self-signed cert in the UI and then applying it, again nginx does not start due to a now freshly missing truenas_default.crt and key missing. I would expect that after assigning the new cert in the ui, that the nginx conf is updated to point to it, not the 100% missing key/cert