According to the page linked by Julian Taylor, it seems it's the single developers' responsibility to choose the correct compiler. I don't know if a workaround might be provided by default - I'm asking in the IRC channels for advice.
** Changed in: gtk-sharp2 (Ubuntu) Status: Incomplete => New ** Description changed: + If you try to execute a .NET program not compiled against Mono 4.0 (but + compiled against Mono 2.0 instead), when you try to run it you get many + exception messages relative to missing methods, such as "Missing method + System.Type::op_Inequality(Type,Type) in assembly + /usr/lib/mono/2.0/mscorlib.dll". + + More details here: <http://orangesquash.org.uk/~laney/blog/posts/2011/10 + /mono-gotcha/> + + Temporary workaround: + Run the application passing the "--runtime=v4.0" switch to Mono, like this: + mono --runtime=v4.0 /usr/lib/myapp/myapp.exe + (where "/usr/lib/myapp/myapp.exe" is the complete path to the program you are trying to execute) to force Mono to use the v4.0 runtime. + ----- + This is a sample scenario (running WepCrack): luis@ubuntu:~$ sudo su - [sudo] password for luis: + [sudo] password for luis: root@ubuntu:/home/luis# cd Escritorio/WepCrack root@ubuntu:/home/luis/Escritorio/WepCrack# sudo ./wepcrack Missing method System.Type::op_Inequality(Type,Type) in assembly /usr/lib/mono/2.0/mscorlib.dll, referenced in assembly /usr/lib/mono/gac/gtk-sharp/2.12.0.0__35e10195dab3c99f/gtk-sharp.dll Unhandled Exception: System.MissingMethodException: Method not found: 'System.Type.op_Inequality'. - at WepCrackGtk.MainWindow..ctor () [0x00000] in <filename unknown>:0 - at GWepCrackGui.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0 + at WepCrackGtk.MainWindow..ctor () [0x00000] in <filename unknown>:0 + at GWepCrackGui.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0 [ERROR] FATAL UNHANDLED EXCEPTION: System.MissingMethodException: Method not found: 'System.Type.op_Inequality'. - at WepCrackGtk.MainWindow..ctor () [0x00000] in <filename unknown>:0 - at GWepCrackGui.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0 + at WepCrackGtk.MainWindow..ctor () [0x00000] in <filename unknown>:0 + at GWepCrackGui.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0 root@ubuntu:/home/luis/Escritorio/WepCrack# ProblemType: Bug DistroRelease: Ubuntu 11.10 Package: gnome-terminal 3.0.1-0ubuntu3 ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4 Uname: Linux 3.0.0-12-generic i686 ApportVersion: 1.23-0ubuntu3 Architecture: i386 Date: Sun Oct 30 21:28:04 2011 ExecutablePath: /usr/bin/gnome-terminal InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007) SourcePackage: gnome-terminal UpgradeStatus: Upgraded to oneiric on 2011-10-24 (6 days ago) ** Summary changed: - Missing method System.Type::op_Inequality(Type,Type) in assembly /usr/lib/mono/2.0/mscorlib.dll + Unable to execute .NET programs compiled against the v2.0 runtime: "Missing method System.Type::op_Inequality(Type,Type) in assembly /usr/lib/mono/2.0/mscorlib.dll" -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/884035 Title: Unable to execute .NET programs compiled against the v2.0 runtime: "Missing method System.Type::op_Inequality(Type,Type) in assembly /usr/lib/mono/2.0/mscorlib.dll" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gtk-sharp2/+bug/884035/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs