Monodevelop build errors (Error CS0518)

[rootPL]

Hi,

I had 31 errors during build of empty project.
Unity version: 5.6.0xf3

There is similar issue registered: Unity Issue Tracker - [Mono Runtime Upgrade] MonoDevelop on OS X produces lots of errors

Also I saw similar topic here: [SOLVED] Dependencies not installed - Unity Engine - Unity Discussions marked as [SOLVED] but solution of installing: sudo apt-get install mono-complete gnome-sharp2 doesn’t seems to work for me as I have already newest version of mono-complete 4.2.1 and version of monodevelop 5.10

My temporary solution is to change csproj file
From: v3.5
To: v4.5
Or it can be changed using:
Project → Assemby-CSharp Options → Build → General → Target ->framework Mono/.Net 4.5

But each time I’m opening monodevelop from Unity this value is overridden back to 3.5
Anyone knows how to set it permamently ?

[Bshsf_9527]

have you solved this problem ?
maybe this link may help you ~
Compiler Error CS0518 | Microsoft Docs

it says that you project has missing some reference of some dlls such as “mscorlib.dll”
you can find this dll in the path of you unity install dir