Compiled mono missing default .NET libraries - System.Object is not defined or imported

Question

I've compiled mono on OS X Mavericks following the guide located here: http://www.mono-project.com/docs/compiling-mono/mac/

Now when I compile my application using xbuild I'm getting the following errors:

CSC: error CS0518: The predefined type `System.Object' is not defined or imported
CSC: error CS0518: The predefined type `System.ValueType' is not defined or imported
CSC: error CS0518: The predefined type `System.Attribute' is not defined or imported
CSC: error CS0518: The predefined type `System.Int32' is not defined or imported
CSC: error CS0518: The predefined type `System.UInt32' is not defined or imported
CSC: error CS0518: The predefined type `System.Int64' is not defined or imported
CSC: error CS0518: The predefined type `System.UInt64' is not defined or imported
CSC: error CS0518: The predefined type `System.Single' is not defined or imported
CSC: error CS0518: The predefined type `System.Double' is not defined or imported
CSC: error CS0518: The predefined type `System.Char' is not defined or imported
CSC: error CS0518: The predefined type `System.Int16' is not defined or imported
CSC: error CS0518: The predefined type `System.Decimal' is not defined or imported
CSC: error CS0518: The predefined type `System.Boolean' is not defined or imported
CSC: error CS0518: The predefined type `System.SByte' is not defined or imported
CSC: error CS0518: The predefined type `System.Byte' is not defined or imported
CSC: error CS0518: The predefined type `System.UInt16' is not defined or imported
CSC: error CS0518: The predefined type `System.String' is not defined or imported
CSC: error CS0518: The predefined type `System.Enum' is not defined or imported
CSC: error CS0518: The predefined type `System.Delegate' is not defined or imported
CSC: error CS0518: The predefined type `System.MulticastDelegate' is not defined or imported
CSC: error CS0518: The predefined type `System.Void' is not defined or imported
CSC: error CS0518: The predefined type `System.Array' is not defined or imported
CSC: error CS0518: The predefined type `System.Type' is not defined or imported
CSC: error CS0518: The predefined type `System.Collections.IEnumerator' is not defined or imported
CSC: error CS0518: The predefined type `System.Collections.IEnumerable' is not defined or imported
CSC: error CS0518: The predefined type `System.IDisposable' is not defined or imported
CSC: error CS0518: The predefined type `System.IntPtr' is not defined or imported
CSC: error CS0518: The predefined type `System.UIntPtr' is not defined or imported
CSC: error CS0518: The predefined type `System.RuntimeFieldHandle' is not defined or imported
CSC: error CS0518: The predefined type `System.RuntimeTypeHandle' is not defined or imported
CSC: error CS0518: The predefined type `System.Exception' is not defined or imported

When I used the mono installer on OS X I never received any of these errors.

(I'm building mono because I'm adding functionality to the .NET framework that wasn't completed)

Result of running autogen.sh: https://gist.github.com/Geesu/149332f3f877c891d387 Result of running make: https://gist.github.com/Geesu/4296f7d4c6c368d6986d

Can you post the actual csc line, and locations of it and the built libraries? — Eris, Dec 25 '14 at 21:01
How can I provide this? I'm not sure how to find the CSC line. Also, I can post the output of the compilation - would that help? — Geesu, Dec 26 '14 at 19:31

score 13 · Answer 1 · answered Jan 09 '15 at 07:02

If there is a warning similar to:

/lib/mono/4.5/Microsoft.Common.targets:  warning : Unable to find framework corresponding to the target framework moniker '.NETFramework,Version=v2.0'. Framework assembly references will be resolved from the GAC, which might not be the intended behavior.

You can override the .NET Framework on the command line:

xbuild /p:TargetFrameworkVersion="v4.0"

You can change your solution:

<TargetFrameworkVersion>v4.0</TargetFrameworkVersion>

score 8 · Answer 2 · answered Aug 12 '16 at 16:58

I ran into this issue while building YouCompleteMe / OmniSharpServer on Debian unstable (Sid). What's happening is the installed version of mono doesn't have the v4.5.2 Framework assemblies installed, which is what the compiler defaults to when building that solution/project.

Workaround is to specify the targeted framework version as one you have available, or make available the one being targeted (e.g. during your custom compilation).

Cat Zimmermann's response is apt.

score 3 · Answer 3 · answered Dec 30 '14 at 12:31

3

I stumpled acros this problem to. I forgot to check for updates after rerunning the Mavericks installer, and there were Stable channel updates available for both Mono and Xamarin.Android. Once I installed them, everything built just fine.

answered Dec 30 '14 at 12:31

Sievajet

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The original poster is talking about a mono installation that is compiled from scratch, not downloaded via Xamarin, or through the mono installer. – Steve Mitcham Dec 31 '14 at 13:35

score 1 · Answer 4 · answered Dec 30 '14 at 22:00

1

The difference with the installer and the home build is the fact that the installer "knows" where the libarys are located, whereas the compiled one dont. So unless you point to that location when compiling your app, your problem will occure (there are basically no system dll's found). I would recommend looking into the mcs documentation , and specify the path. (EDIT: with the "-L " parameter should do it.).

answered Dec 30 '14 at 22:00

Kmtdk

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I wouldn't need the mcs tool. I'm trying to compile mono itself. I'm adding functionality to it that hasn't been completed. – Geesu Dec 31 '14 at 21:36

score 1 · Answer 5 · answered Oct 17 '15 at 02:43

1

my project started compiling, when I removed lines

<NoStdLib>true</NoStdLib>
<NoConfig>true</NoConfig>

from it.

answered Oct 17 '15 at 02:43

user1709408

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score 1 · Answer 6 · answered Feb 24 '18 at 14:15

1

I don't know how to back this logically, but after trying to fix this for couple of hours,

Unload .net standards project

because I was not getting the exact problem and decided to

reload it again

boom... It worked... still don't know what is the logical reason behind it. if someone does, please comment below.

answered Feb 24 '18 at 14:15

Akshay Kulkarni

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weird, but it worked ! Thanks! – Sandro Stadler Jul 13 '22 at 12:50

score 1 · Answer 7 · answered May 31 '18 at 15:16

1

Try deleting bin and obj folders in all projects of that solution.

Seems like those folders were having old files generated by some older version of visual studio, which are not compatible with new version of visual studio.

answered May 31 '18 at 15:16

Jay Shah

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score 0 · Answer 8 · answered Sep 04 '18 at 07:45

0

I solve this problem by change the project setting->general->Target Framework to Mono/.NET 4.5.

Hope it works for you.

answered Sep 04 '18 at 07:45

sam

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score 0 · Answer 9 · edited Oct 01 '21 at 17:58

0

I had the same problem.

I checked my Target Framework Path: Properties>Aplication:Target Framework and set it to .Net Framework 4.7.

edited Oct 01 '21 at 17:58

XouDo

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answered Oct 01 '21 at 07:45

Lila Kumari Yadav

1

Compiled mono missing default .NET libraries - System.Object is not defined or imported

9 Answers9