Microsoft.Bcl.Async package breaks VS 2012 designer - by Michael Melancon

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ID 782147 Comments
Status Active Workarounds
Type Bug Repros 2
Opened 3/26/2013 8:18:11 AM
Access Restriction Public


After installing the Microsoft.Bcl.Async package from NuGet, I get the following error, which stops my controls from displaying in the VS design view.

Error	Could not load file or assembly 'System.Core, Version=, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, Retargetable=Yes' or one of its dependencies. The system cannot find the file specified.

The dll that the components that cause the problem are in, references the System.Core dll as follows:

<Reference Include="System.Core">

Other reports online of the same problem:
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Posted by Hagelt18 on 4/18/2013 at 11:12 AM
We struggled with an issue very similar to this for a while. We had our programs set up with 4.0 and the Microsoft.Bcl.Async package installed. It worked fine on Windows 7/Server 2008 and up, but it would crash during run time when we tried running it on Windows Xp or Server 2003 even though they had all the frameworks up to 4.0. Eventually we discovered this article:

It suggested we get the latest 4.0 patch (KB2468871). After installing the patch the error went away. Hope this helps others who run into this error.
Posted by Macy [MSFT] on 4/2/2013 at 2:39 AM
Hi, given that we have not heard back from you in 7 days. We will go ahead and close this Connect Issue. If you get a chance to review and provide the information requested earlier, you can go ahead and reactivate this issue.
Posted by Macy [MSFT] on 3/29/2013 at 12:42 AM
I am currently standing by for an update from you and would like to know how things are going on your end. If you could get back to me at your earliest convenience with information I request, we will be able to make headway towards a resolution. I look forward to hearing from you.
Posted by Macy [MSFT] on 3/26/2013 at 10:33 PM
Thank you for submitting feedback on Visual Studio and .NET Framework. In order to efficiently investigate and reproduce this issue, we are requesting additional information outlined below.

Could you please give us a demo project to demonstrate this issue so that we can conduct further research?

Please submit this information to us within 4 business days. We look forward to hearing from you with this information.

Microsoft Visual Studio Connect Support Team
Posted by Helen [MSFT] on 3/26/2013 at 8:51 AM
Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(