NzbDrone.master.2.0.0.4230.mono.tar.gz
–followed this guide on CentOS 7 - Minimal
[machine opt]# systemctl status sonarr
● sonarr.service - Sonarr Daemon
Loaded: loaded (/usr/lib/systemd/system/sonarr.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Sun 2016-07-31 04:25:17 EDT; 4s ago
Process: 6682 ExecStart=/usr/bin/mono --debug /opt/sonarr/NzbDrone.exe -nobrowser -data /opt/sonarr (code=exited, status=1/FAILURE)
Main PID: 6682 (code=exited, status=1/FAILURE)
/usr/lib/systemd/system/sonarr.service
http://pastebin.com/A9Pc1SzE
Clean install of CentOS7, installed, only thing changed was the user in the daemon
Starting mono manually
/usr/bin/mono --debug /opt/sonarr/NzbDrone.exe
http://pastebin.com/3DxEmyJt
I can curl the Address hostname:8989 and it’s obvious that there is a webpage there concerning Sonarr. Opening up the console in Google, receiving a
GET http://bos-oracle:8989/ 500 (Internal Server Error)
Permissions seem to be good on all the files, but I’m not sure where I’m running into the hiccup
[ANSWER]
Sometimes you just need to keep trying things 
Valdis Kletnieks took the win on this one! https://bugzilla.redhat.com/show_bug.cgi?id=1313021
Changing the /etc//mono/config line 13 (the one with MonoPosixHelper) to the following;
<dllmap dll="MonoPosixHelper" target="/usr/lib64/libMonoPosixHelper.so" os="!windows" />
Looks like Mono was updated and this line not correctly pointing to the libMonoPosixHelper was giving Sonarr trouble