Mod works fine on Linux but not on Windows (System.MissingMethodException)

[Anluin]

Hi, I'm developing my first mod right now and I'm just about to finish.
I developed and tested the mod under Linux (everything worked so far).
Now wanted to try with my friend whether everything works as it should in multiplayer: it turned out that the mod does not work on Windows.

The following error is thrown:

Critical error occurred
System.MissingMethodException: Methode nicht gefunden: "Void System.Collections.Generic.KeyValuePair`2.Deconstruct(!0 ByRef, !1 ByRef)

For compiling I use the "mono/4.5" framework; I've been thinking about going down to "mono/4.0", but that would mean I'd have to completely rewrite the mod.

I also have to admit that I haven't had anything to do with the .NET ecosystem for a very long time and I have absolutely no idea how to tackle the problem down.