Bug 56488 - An assembly `System.Core' with the same identity has already been imported.
Summary: An assembly `System.Core' with the same identity has already been imported.
Alias: None
Product: Visual Studio Extensions
Classification: Xamarin
Component: iOS ()
Version: unspecified
Hardware: PC Windows
: --- normal
Target Milestone: 15.3
Assignee: Bugzilla
Depends on:
Reported: 2017-05-16 10:07 UTC by nazar
Modified: 2017-07-21 09:50 UTC (History)
11 users (show)

Is this bug a regression?: ---
Last known good build:

NativeLibraryBinding test empty project with reproduces the issue (4.68 KB, application/x-zip-compressed)
2017-05-16 10:07 UTC, nazar
Verbose Build Log (128.46 KB, text/plain)
2017-05-16 17:18 UTC, nazar

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.

Please create a new report on Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:

Description nazar 2017-05-16 10:07:01 UTC
After updating to latest version of xamarin we've got the following problem

An assembly `System.Core' with the same identity has already been imported. Consider removing one of the references SciChart.iOS.Charting

Please see the system information 

Microsoft Visual Studio Community 2017 
Version 15.2 (26430.6) Release
Microsoft .NET Framework
Version 4.6.01586

Installed Version: Community

Mono Debugging for Visual Studio   Mono.Debugging.VisualStudio
Support for debugging Mono processes with Visual Studio.

Xamarin (c871575)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin.iOS and Xamarin.Mac SDK (30b6e87)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.
Comment 1 nazar 2017-05-16 10:07:56 UTC
Created attachment 22192 [details]
NativeLibraryBinding test empty project with reproduces the issue
Comment 2 nazar 2017-05-16 10:08:09 UTC
Please see the attachment
Comment 3 Vincent Dondain [MSFT] 2017-05-16 14:32:29 UTC

Simply building this empty binding project which reference System.Core gives you a build error?

I couldn't reproduce that with the following environment: https://gist.github.com/VincentDondain/91b1d7565cb379f5dbc96aa1996da459

Could you please give us your full build log (in verbose mode if possible)?

Might be a Xamarin Visual Studio Windows issue.
Comment 4 nazar 2017-05-16 14:53:02 UTC
Hi Vincent,

Is there a way to set -v -v -v -v to a xamarin.iOS binding project? because afaik I can set it only in the actual xamarin.ios application.

The log I can see without any changes is the following

1>------ Build started: Project: NativeLibraryBinding, Configuration: Debug Any CPU ------
1>  Connecting to Mac server
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\Xamarin\iOS\Xamarin.iOS.ObjCBinding.CSharp.targets(60,3): error : An assembly `System.Core' with the same identity has already been imported. Consider removing one of the references
1>  /Users/admin/Library/Caches/Xamarin/mtbs/builds/NativeLibraryBinding/6351ac7c7b0e7a8b1956de01c5c7cb48/bin/Debug/System.Core.dll (Location of the symbol related to previous error)
1>  System.Core.dll (Location of the symbol related to previous error)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Best Regards
Comment 5 Vincent Dondain [MSFT] 2017-05-16 16:22:14 UTC
We don't have a UI option the add extra arguments to btouch/bmac yet (will come).

However, I still believe you can give us a more verbose build log which will greatly help us.

You should be able to change the build verbosity here:

Tools > Options > Projects and Solutions > Build and Run

I assume you indeed got this issue with a simple new binding project on Visual Studio Windows and since I can't reproduce that with similar product versions on the Mac I'll reassign to the XVS team.
Comment 6 nazar 2017-05-16 17:18:39 UTC
Created attachment 22209 [details]
Verbose Build Log
Comment 7 nazar 2017-05-16 17:19:03 UTC
Please see the attached log
Comment 8 Vincent Dondain [MSFT] 2017-05-19 10:56:32 UTC
Full build log provided, resetting to NEW.

Comment 9 nazar 2017-06-01 15:47:38 UTC
hi guys, Is there anything happening in order to fix this?
Comment 10 Emanuel 2017-06-08 13:53:03 UTC
Fixed on master and d15-3: 6866237f838136f18c5cda9b0af5d932af70df7f
Comment 11 nazar 2017-06-08 13:55:00 UTC
is there any ETA into our hands?
Comment 12 Emanuel 2017-06-08 14:18:32 UTC
Hi Nazar,
Unfortunately there isn't a release date for 15.3 yet, but there will probably be an Alpha Preview next week.
Comment 13 nazar 2017-06-08 14:22:27 UTC
Hi Emanuel, thanks for the help. 

Hopefully, we will see it released soon :) At lease hope it will fix this problem in alpha:)

Have a good day.

Best Regards,
Comment 14 Neeraj Deshmukh 2017-07-14 10:22:17 UTC
Nazir, Can you help me with specific steps to replicate issue?  I believe you occurred issue while binding project on Visual Studio, please confirm my statement.
Comment 15 nazar 2017-07-14 15:40:13 UTC
hi Neeraj, I can confirm that. But isn't it fixed in 15.3?

best regards,
Comment 18 Christian Schwarz 2017-07-21 09:50:32 UTC
Hi Neeraj, is this already in VS 15.3.0 Preview 4?