Sonarr crashing after updating Mono

[PimpChicken]

Sonarr version (exact version):
v2.0.0.5228
Mono version (if Sonarr is not running on Windows):
5.12.0.226
OS:
Linux 3.2.58-2 (Drobo 5N) running on Marvell ARM CPU
BusyBox v1.23.2
Debug logs:
https://hastebin.com/ruqexaqafu.pas
Description of issue:
After updating Mono to 5.12 in the Drobo Dashboard (I believe I had version 3.x before), Sonarr will no longer launch. It is complaining about a missing libMonoPosixHelper.so at /mnt/DroboFS/Shares/DroboApps/mono/lib/…//libMonoPosixHelper.so, however I believe the extra …/ in the path is messing it up (I have confirmed the file exists at /mnt/DroboFS/Shares/DroboApps/mono/lib/libMonoPosixHelper.so).

[markus101]

That’s a problem with the mono install, drobo forums/support/whatever may be able to help. The path looks a little weird with 2 slashes in it.

[PimpChicken]

I found a fix to the issue (although it’s very strange why this works):

I opened up /mnt/DroboFS/Shares/DroboApps/mono/etc/mono/config in vi and found this line:

<dllmap dll="MonoPosixHelper" target="$mono_libdir/libMonoPosixHelper.so" os="!windows" />

I checked and $mono_libdir wasn’t actually set, so I set it to /mnt/DroboFS/Shares/DroboApps/mono/lib and tried starting Sonarr again, no dice.

What ended up fixing it was entering the full path to libMonoPosixHelper.so:

<dllmap dll="MonoPosixHelper" target="/mnt/DroboFS/Shares/DroboApps/mono/lib/libMonoPosixHelper.so" os="!windows" />

Very strange!