Comment 2 for bug 882501

Some statements I found in a series of web searches suggest that Oneiric uses the CLI 4.0 runtime, and thus required using the appropriate compiler for C# code and appropriate settings in Monodevelop. According to them, you should use the dmcs compiler instead of gmcs. There is also a specific setting in Monodevelop to compile for the 4.0 CLI runtime.

I managed to verify that, on Oneiric, a simple hello world window application using GTK# compiles with dmcs on the command line and run without the error shown above. If I use gmcs to compile it, it throws the same exception and crashes the same way as above.

I learned that dmcs is the compiler to use for CLI 4.0 from here:

http://mail.gnome.org/archives/banshee-list/2011-October/msg00044.html

The 2nd message here recommends setting the "build -> runtime version" option in Monodevelop to Mono / 4.0. :

http://comments.gmane.org/gmane.comp.gnome.mono.general/42196

I haven't tested the Monodevelop setting yet, because I haven't yet installed it on my computer. Dmcs is in the mono-dmcs package.