1

Unity includes Mono.Security.dll and System.dll as of 4.2.2f1.

Upgraded from 4.2 to 4.3.0f4 but still have Mono.Security.dll and System.dll in build. Tested a empty project and they are not included.

So most likely I have some script depending on them.

In order to find them, I deleted System reference in Mono as stated in this Answer, but rebuilding succeeded.

Is there any other way to find which script depend on System.dll?

2

Use ildasm.exe (at least, on windows, monodis is similar on mono platform: http://mono-project.com/Dis/Assembling_CIL_Code).

C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\ildasm.exe

I recommend to “Dump Tree” (File menu) to a test file, then search for the referenced assembly (“[System]”) or namespace. It will show you the class and probably the method referencing the assembly.

As of 4.3, you don’t have to care about
“[System.Core]System.Runtime.CompilerServices.ExtensionAttribute”
which is caused by using extension methods. This is not a “real” reference, and you can use your build without System.Core.dll.