c# – System.ObjectModel Warning Xamarin does not run on Android-ThrowExceptions

Exception or error:

We are running the ‘Welcome to Xamarin` example on Visual Studio Enterprise, using the latest Xamarin, in a Windows 8.1 environment.

We are managing to build and run on both Windows and Apple, but we are facing problems with Android.

The referenced component System.ObjectModel could not be found.

The errors can be seen in the screen shot below:

See screenshot

We’ve already tried searching online for solutions, we found some, which we tried, but to no avail.

On the other hand, is Xamarin compatible with Windows 8.1? Perhaps some Android requirement actually needs a Windows 10 environment.

Any help would be appreciated.

How to solve:

Right click on your Android project’s references and manually add the reference: C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\MonoAndroid\v1.0\Facades\System.ObjectModel.dll. And technically that’s a warning, not an error.


I simply removed the reference entirely since none of my code actually used it.


In the Package manager console type: (Select the Android project)

update-package -reinstall

Is slower but is the correct method and always works


Exercise 1 from GitHub https://github.com/XamarinUniversity/XAM135/
when opening has the same problem.

Based on the above solutions I resolved by performing the following steps:

  1. Update the Nuget Package

  2. Save, close and abire the solution

  3. Click on the Portable (shared) project-> Referencias-> Donet in the copy properties of the path = “C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETPortable\v4.5\Profile\Profile111”

  4. Open Windows Explorer and paste the path = “C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETPortable\v4.5\Profile\Profile111”, here is the System.ObjectModel.dll file

  5. Click on the Droid Project -> Referencias and REMOVE System.ObjectModel

  6. Right click on References and Add references

  7. Click the Browse button and open the path = “C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETPortable\v4.5\Profile\Profile111”

  8. Select System.ObjectModel.dll, and then click Add and OK

  9. The reference was added successfully! Save, compile the project.

Here is a similiar solution


Try moving it to desktop, then add it as ref in solution. worked for me, visual studio had access to all the other ref but for some reason dident have access to that specific ref. So i moved it, and i think it gave visual studio access. simply try to move it where access wont be a problem.


Copy dll and paste to packages folder. Change reference to new location and run project. Of course it’s temporary solution. You can check another location for path without white spaces in folders name.


yes, you are partially correct, it works, but after again giving to old location (C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\ReferenceAssemblies\Microsoft\Framework\MonoAndroid\v1.0\Facades\System.ObjectModel.dll) missing error resolved.

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