NzbDrone doesn't start on FreeBSD

You have to mount procfs.

mount -t procfs procfs /proc

That solved this issue for me. NLog must request some sort of manual process management and that causes the error.

% uname -a
FreeBSD swordfish 10.0-RELEASE FreeBSD 10.0-RELEASE #0 r260789: Thu Jan 16 22:34:59 UTC 2014     root@snap.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64
% mono NzbDrone.exe

Press any key to exit…

% mount -t procfs procfs /proc
% mono NzbDrone.exe
[Info] Bootstrap: Starting NzbDrone - /usr/home/bkoepke/NzbDrone/NzbDrone.exe - Version 2.0.0.1690
[Info] MigrationLogger: *** Migrating data source=/home/bkoepke/.config/NzbDrone/nzbdrone.db;cache size=-10485760;datetimekind=Utc;journal mode=Wal ***
[Info] MigrationLogger: *** Migrating data source=/home/bkoepke/.config/NzbDrone/logs.db;cache size=-10485760;datetimekind=Utc;journal mode=Wal ***
[Info] Router: Application mode: Interactive
[Info] OwinHostController: Listening on the following URLs:
[Info] OwinHostController:   http://*:8989/
[Info] NancyBootstrapper: Starting NzbDrone API