Announcing the .NET Framework 4.5.1 RC

Announcing the .NET Framework 4.5.1 RC

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Update: The .NET Framework 4.5.1 RTM has been released and is available for download.

The .NET Framework 4.5.1 RC is now available. It comes with a go-live license, enabling you to deploy 4.5.1 apps in production.

Here are the RC bits. Download them. Try them out. Tell us what you think.

Our RC release is a set of “fit and finish” changes on top of the earlier .NET Framework 4.5.1 Preview, which we released in June. The best place to learn about the features and capabilities of RC is to read our earlier .NET Framework 4.5.1 Preview post. Our plan was to complete all new 4.5.1 features in the Preview release, and then to polish them on our way to RTM. That’s exactly what you see playing out with the RC release.

You can also check out our What's New in the .NET Framework 4.5 MSDN page, which calls out new 4.5.1 features. Still, if you are a TL;DR type of reader, I’ll call out some of the big features here, in the three categories that we focused on. They are all waiting for you in the new release.

  • Developer productivity
    • x64 edit and continue
    • Async-aware debugging
    • Managed return value inspection
    • ADO.NET idle connection resiliency
    • Improvements in Windows Store app development
  • App performance
    • ASP.NET app suspension
    • On-demand large object heap compaction
    • Multi-core JIT improvements
    • Consistent performance before and after servicing the .NET Framework
  • Continuous innovation
    • .NET Framework updates
    • NuGet releases
    • Better discoverability of Microsoft .NET NuGet packages
    • Supporting large scale deployment of .NET NuGet packages

The .NET Framework 4.5.1 is gathering momentum. We can tell that just from the download numbers, but also from the developers that we’ve been talking to. Do check out the 4.5.1 RC, even if you haven’t tried the Preview release. Please tell us how the .NET Framework 4.5.1 is working out for you. We’d love to get your feedback.

We also announced that the .NET Framework 4.5.1 and Visual Studio 2013 will RTM with Windows 8.1 GA. You can read more about the launch on Soma’s blog.

Update (2013/9/9 10:45AM): Windows GA is 2013/10/18. .NET 4.5.1 RTM will be available on the same day. Read Gugg’s post for some more info on the rollout. He also announces that you can download Windows 8.1 and Windows Server 2012 R2 (both RTM versions) starting today.

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  • Dear .NET team, thank you so much for the updates.

    In your future efforts, please consider implementing best and most optimized algorithm for Age() in DateTime class. Being a common problem and due to its inherit complexity (, please consider it for .NET framework:

    This definitely would make sense if "current age" of any DateTime object can be retrieved and the function is defined in the DateTime class. This would bring great deal of value to .NET framework.

  • ¡Al fin! Esperaba con ansia la actualización, pronto la tendré en mi equipo y trabajaré feliz.

  • Excellent Post. Also visit

  • I was hoping the "TL;DR" of an article about the updates in 4.5.1 would have been a bit more than ".NET Framework updates".

  • I appreciate the gift of .NET 4.5.1 guys, really.  But my birthday is October 19th.  ;)

  • Thank you for Sharing Annuouncing the .NET Framework 4.5.1 RC hoping in future too

  • Good 2have'1

  • The advice for detecting 4.5.1 is incorrect, as on an actual 8.1 machine, you'll see a release of 378675, not 378758.

    Installing the packages won't help.


  • very helpful

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