Crash on FC20 - Object reference not set

I am occasionally getting the below error, it seems to be borking while doing an rss sync.
This is on Fedora 20, what information do you need from me in order to figure out what is going on ?

[Info] DownloadDecisionMaker: Processing 310 reports
EPIC FAIL: System.NullReferenceException: Object reference not set to an instance of an object
at System.Threading.EventWaitHandle.Reset () [0x00000] in :0
at (wrapper remoting-invoke-with-check) System.Threading.EventWaitHandle:Reset ()
at System.Threading.Timer+Scheduler.SchedulerThread () [0x00000] in :0
at System.Threading.Thread.StartInternal () [0x00000] in :0
[Fatal] GlobalExceptionHandlers: EPIC FAIL: Object reference not set to an instance of an object

System.NullReferenceException: Object reference not set to an instance of an object
at System.Threading.EventWaitHandle.Reset () [0x00000] in :0
at (wrapper remoting-invoke-with-check) System.Threading.EventWaitHandle:Reset ()
at System.Threading.Timer+Scheduler.SchedulerThread () [0x00000] in :0
at System.Threading.Thread.StartInternal () [0x00000] in :0

[ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object
at System.Threading.EventWaitHandle.Reset () [0x00000] in :0
at (wrapper remoting-invoke-with-check) System.Threading.EventWaitHandle:Reset ()
at System.Threading.Timer+Scheduler.SchedulerThread () [0x00000] in :0
at System.Threading.Thread.StartInternal () [0x00000] in :0
Stacktrace:

Native stacktrace:

    /opt/mono/bin/mono() [0x4f4a58]
    /opt/mono/bin/mono() [0x55aa83]
    /opt/mono/bin/mono() [0x46aec2]
    /usr/lib64/libpthread.so.0() [0x3946e0f6d0]
    [0x2923350]

Debug info from gdb:

warning: unable to open /proc file '/proc/7059/status’
warning: unable to open /proc file '/proc/7059/status’
ptrace: No such process.
No threads.

NzbDrone]# /opt/mono/bin/mono -V
Mono JIT compiler version 3.12.0 (tarball Thu Jan 15 08:07:24 UTC 2015)
Copyright © 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
TLS: __thread
SIGSEGV: altstack
Notifications: epoll
Architecture: amd64
Disabled: none
Misc: softdebug
LLVM: yes(3.4svn-mono-/)
GC: sgen

Which version of Sonarr?

This is failing within mono, not sure how much we’re going to be able to investigate, though we’re making some improvements in how we run background jobs, which might help here.

Latest stable. 2.0.0.2850

It’s being a bit quirky with some downloads … I think I have the correct mono version but the default one is also installed for another program.
I’m still fairly new to Sonarr, so far I’ve always just manually downloaded stuff so still trying to figure everything out.