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The Microsoft .NET Framework 4.5.1 (Offline Installer) is now available for the .NET Framework 4 and the .NET Framework 4.5.

If your computer is not connected to the Internet, you can use the offline installer instead of the web installer to install this update. However, we recommend that you use the web installer to install this update if you are connected to the Internet. The .NET Framework 4.5.1 (Offline Installer) package is larger than the .NET Framework 4.5.1 (Web Installer) package.

The .NET Framework 4.5.1 Language Pack contains localized resources for supported languages. It contains translated error messages and other UI text for languages other than English. If you don't install a language pack, this text is displayed in English. You can install multiple language packs on one computer, each for a different language.

You must download and install the .NET Framework 4.5.1 (Offline Installer) before you install the language packs.

More Information

Download information

The following files are available for download from the Microsoft Download Center:

The .NET Framework 4.5.1 (Offline Installer)

Download Download the package now.

The .NET Framework 4.5.1 Language Packs (Offline Installer)

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 Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

What is new in the .NET Framework 4.5.1?

The .NET Framework 4.5.1 supports the use of C#, Visual Basic, and F# code. Additionally, the .NET Framework 4.5.1 provides the following language and framework improvements:

  • Performance and reliability improvements

  • The ability to suspend and resume operations in the ASP.NET page framework

  • The ability to compact large object heaps on-demand

  • 64-bit Edit and Continue controls

  • The ability to trace and sample activities

  • Improvements that make SQL connections more resilient

  • The ability to manage return values

For more information about these and other features of the .NET Framework 4.5.1, go to the following Microsoft websites:

The .NET Framework Developer Center

The .Net Framework Blog

The .NET Framework 4.5.1 runs side-by-side with the .NET Framework 3.5 Service Pack 1 (SP1) and earlier versions of the .NET Framework. However, the .NET Framework 4.5.1 is an in-place update for the .NET Framework 4 and the .NET Framework 4.5.

Command-line switches 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 on the following MSDN website:

.NET Framework Deployment Guide for Developers

Restart requirement

You may have to restart the computer after you install this update. We recommend that you close all applications that are using the .NET Framework before you install this update.


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

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