No async/await keywords with VS Async CTP for VS2010 on Windows 10

MeThomas-1770 0 Reputation points


although it should be an old hat and I "should upgrade to a newer version" etc. I did not find any solution.

Is it the Windows 10 64 bit? Installed is Windows 10 Pro 64 bit 22H2 version 10.0.19045, build 19045.3693.

VS2010 Ultimate with surely all possible updates installed with the extensions NuGet Package Manager, PowerCommands for Visual Studio 2010, Productivity Power Tools.

VS2010 SP1 installed with NuGet Package Manager.

VS2012 Express, 2013, 2017, 2022 - all Community - installed.

MS download link results in downloading Async-CTP-v3.exe , installed without shown problems but with a - later - closer look it asked me if I want to execute Async-CTP-v2.exe ... Is it this?

The hints on

are only partial to be found in the archives and so I could not check if the versions of the mentioned files are correct. I still did not try the installation on a virtual machine with an old Windows.

Thank you,


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  1. Tianyu Sun-MSFT 29,356 Reputation points Microsoft Vendor

    Hello @MeThomas-1770,

    Welcome to Microsoft Q&A forum.

    Visual Studio 2010 doesn’t support C# 5 and .NET Framework 4.5, the async/await keywords were introduced in C# 5 and .NET Framework 4.5, so either you need to install Visual Studio Async CTP or update to use a higher version of Visual Studio like VS 2012, VS 2013…(the NuGet package Microsoft.Bcl.Async supports using async/await keywords without .NET Framework 4.5, but this NuGet package needs Visual Studio 2012).

    If you choose to install Visual Studio Async CTP, ideally, it works, otherwise you may face many issues, as it’s also a very old package/update/installer. For example, you have successfully installed it without prompting any errors, but async/await keywords still don’t work, or partly work. In this situation, it’s difficult to continue, as installing is successful. You have no choice(the solution may be to install a newer version of the Async CTP, but it doesn’t have a newer version for you to update) but using it.

    I know you mentioned at the very beginning of your question, but I would still suggest using a higher version of Visual Studio.



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