Visual Studio 11 Developer Preview - Project Backward Compatibility (Round-Tripping)

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Visual Studio 11 Developer Preview - Project Backward Compatibility (Round-Tripping)

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[ NOTE:  This post has been depricated.  The new, updated post can be found here: ]




UPDATE 3/8/2012:  As of the Beta this does not work with all project types.  Most notably web projects are not supported currently for this feature.  For more information on what is supported and what isn't look here:


Probably one of the most welcome new features in VS11DP is the new project backward compatibility feature also known as project round tripping.  Let’s dig into the details.


The Old Days

In all prior incarnations of Visual Studio if you had an older version, VS2008 for example, and opened up the project in a newer version, VS2010 in this case, you had the option to convert the project.  If you did the conversion it was a one-way trip.  You couldn’t open the project again in VS2008 if you tried to go back.  This has been the source of a lot of pain and suffering for developers who have to work with multiple versions of Visual Studio.  We want the cool features of the latest IDE but still want others on our team to be able to open the solution in the older version of Visual Studio when they get the files from source control.


The New, Happy Days

You can now create projects in Visual Studio 2010 with Service Pack 1 then open those projects in Visual Studio 11 Developer Preview and THEN open the project up again in VS2010SP1.  In other words, we now have full project round-tripping capability so you can work with the latest features but still keep the solution compatible with and older version of Visual Studio. 


Putting it to the Test

Here are the steps you can take to test this for yourself:

  1. Create a project with Visual Studio 2010 with Service Pack 1 and put in a little sample code.
  2. Save and close the solution.
  3. Open the solution (CTRL + SHIFT + O) in Visual Studio 11 Developer Preview and add some more code.  Notice there is no longer a prompt to convert the project that appears.
  4. Save the close the solution.
  5. Open the project up again in VS2010SP1 and bask in the glory of project round-tripping.


Limitations / Observations

  • I know this works with Visual Studio 2010 Service Pack 1 but haven’t tested VS2010 with out the service pack.  I believe it will not work unless you have the service pack but am checking with the team.
  • You can’t use this feature with versions older than VS2010.
  • When you use any feature specific to the new version of Visual Studio, like changing the Framework to the latest version, then the project cannot be opened in the prior version.  I just changed the framework version from 4.0 to 4.5 for a project and saved it without many any other change and was not able to open the solution in VS2010.
  • Hi,

    Just installed the beta, the startup page throws a XAML error.

    Should I be able to open VS2008 & 2010 projects in VS11 beta? I can't on the ones I've tried.

  • I have vs 2011 Ultimate Beta SLN but can not open same SLN in VS2010 Sp1.

    ALthough cs.proj project file can be opened in vs2010 but need to chg .net framework from 4.5 to 4.0;

    Can any one help open same SLN created in Vs2011 in vs 2010? THX

  • What projects do you have in the solution?  Not all project types are supported yet.

  • Console Application in VS2011 Ultimate Beta. and need to open Sln in VS2010sp1; Thx

  • Ahhh.  I see the issue.  Okay let me break it down:

    1.  If you start a project/solution in VS2010SP1 it will open in VS11 without making changes that prevent you from re-opening it in VS2010SP1.  So full round tripping is supported.

    2.  If you start a project/solution in VS11 it will NOT open in VS2010SP1 due to the changes in the proj/sln files.  To my knowledge there is no setting to indicate you are going to go back to a prior version of VS that would prevent the new proj/sln type from being used.

    So the project round trip feature is a forward-only activity today.  I'm not sure it will change or what the plans are for multiple versions going forward.  I suspect as we keep doing this feature that, much like the Framework, you will be able to go back and forth a bit more but that is just a guess.

  • Thanks for the update, Sir! Very much appreciated.

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