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I need to install version 3.5 of the .NET Framework in Windows 7, but when I try to install it, it shows the following error:

"Turn on/off .NET Framework" option in System Features

I tried doing this, but I don't understand what it means. Can anyone help me?

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migrated from Mar 7 '11 at 9:23

This question came from our site for professional and enthusiast programmers.

That message is trying to tell you that you need to install .NET 3.5 a different way under Windows 7. Because it's included as part of the operating system, you use the "Turn Windows features on or off" function to get to it, instead of installing a downloaded redistributable package.

  1. Open the Start menu and click "Control Panel".
  2. Under the "Programs" category, click the "Turn Windows features on or off" link text.

  Click "Turn Windows features on or off"

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It is already turned on in my system and I don't see any entry for .net 3.5 in Control Panel programs list? – teenup May 16 '14 at 19:30
@teen If the box is checked, why do you think .NET 3.5 is not already installed? I don't remember whether it shows up in the list of installed programs or not. It doesn't make sense that it would, considering it shows up as a Windows feature... – Cody Gray May 17 '14 at 9:15
@CodyGray I am using Windows 7. And I am going to develop ASP.NET webisite in Visual Studio. For me also dotnet framework 3.5.1 was checked in windows features. But when I am debugging/running that code, from Visual studio it is saying access is denied. But when I am creating a website using dotnet version 4.0 I can successfully run the asp code. I think there is some issue regarding dot net 3.5 framework. Can you please help? – Man_From_India Dec 9 '14 at 7:16

Run the following command as an admin:

DISM /Online /Enable-Feature /FeatureName:NetFx3 /NoRestart

That'll install .NET Framework 3.5 SP1, 3.0 SP1, & 2.0 SP1 ... same as enabling it through the GUI in Control Panel.

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Note: In Windows 7, /All is not a valid option, just leave it out. – Ƭᴇcʜιᴇ007 Aug 7 '15 at 12:46

You may disable/re-enable the Microsoft .NET Framework 3.5.1 within the Control Panel to effectively repair it:

Control Panel > Programs and Features > Turn Windows feature on or off.

Uncheck the Microsoft .NET Framework 3.5.1 entry. Click OK to accept this setting and return to Turn Windows Features on or off to re-enable Microsoft .NET Framework 3.5.1 by checking the box.

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Windows 7 comes with .NET 3.5 you just need to enable it in Windows Features.It gets installed,it selects automatically what else needs to be installed

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