The Microsoft .NET Framework 4.5.1 Developer Pack for Windows Vista SP2, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2008 SP2, Windows Server 2008 R2 SP1, Windows Server 2012 and Windows Server 2012 R2

Applies to: Windows Vista Service Pack 2Windows 7 Service Pack 1Windows 8


The Microsoft .NET Framework 4.5.1 Developer Pack installs the multi-targeting pack for the .NET Framework 4.5.1. Developers can build applications targeting the .NET Framework 4.5.1 by using either Visual Studio 2012 or third-party IDEs.

Note This package should not be used if you intend to redistribute the .NET Framework 4.5.1. In that case, you should download the web installer from here.

More Information

This package installs the following components:
  • The .NET Framework 4.5.1
  • The .NET Framework 4.5.1 Multi-Targeting Pack: Contains the reference assemblies needed to build apps that target the .NET Framework 4.5.1.
  • The .NET Framework 4.5.1 Language Packs
  • The .NET Framework 4.5.1 Multi-Targeting Pack Language Packs : Contains the IntelliSense files to display help while you are building apps that target the .NET Framework 4.5.1 through Visual Studio and third-party IDEs.

Download information

The following file is available for download from the Microsoft Download Center:
Download Download the package now.

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591 How to obtain Microsoft support files from online services
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What’s new in the .NET Framework 4.5.1?

The .NET Framework 4.5.1 supports the writing of code in C#, Visual Basic, and F# programming languages, and includes these significant language and framework improvements:
  • Better performance and reliability
  • ASP.NET application suspend and resume
  • On-demand compaction of the large object heap
  • 64-bit Edit and Continue
  • Activity tracing and sampling
  • SQL connection resiliency
  • Managed return values
For more information about these and other features of the .NET Framework 4.5.1, see the .NET Framework Developer Center website and blog post. This version of the .NET Framework runs side-by-side with the Microsoft .NET Framework 3.5 Service Pack 1 (SP1) and earlier versions, but performs an in-place update for the .NET Framework 4 and the .NET Framework 4.5.

Command-line options for this update

For more information about the various command-line options that are supported by this update, go to the "Command-Line options" section of the following MSDN website:

Supported languages for this update

For more information about the languages that are supported by this update, go to the "Supported Languages for Developer Pack" section of the following MSDN website:

Restart requirement

You may have to restart the computer after you install this software if any affected files are being used. We recommend that you close all applications that are using the .NET Framework before you apply this update.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.