Microsoft .NET Framework is a collection of programming codes required for applications built using the .NET Framework technology to function properly.

The .NET framework consists of a common language runtime that manages various things. For example, memory usage when you execute a .NET based application. It also functions as a .NET Framework class library that contains a collection of reusable codes developers can benefit from during the application development process.

Each edition of Windows can have different versions of the .NET Framework installed or enabled / disabled.

Windows 11

• .NET Framework 3.5 is no longer available in the optional features.
• Use a Powershell command to turn the feature on:
  • Enable-WindowsOptionalFeature -Online -FeatureName NetFx3 -All 

Windows 8.1, Windows 10 and Windows Server 2012 R2

• .NET Framework 4.5.1 is an operating system component that is installed by default.
• .NET Framework 3.5 SP1 is an operating system component that isn’t enabled by default. You can enable it in Programs and Features.

Windows 8 and Windows Server 2012

• .NET Framework 4.5 is an operating system component that is installed by default.
• .NET Framework 3.5 SP1 is an operating system component that isn’t enabled by default. You can enable it in Programs and Features.

Sage 300 CRE and Sage Estimating require that you enable the Microsoft .NET Framework 3.5 SP1 to install and function properly.

To enable .NET 3.5 SP1 on a Windows 8.x operating system, perform the following steps below:

1. Open Control Panel, Program and Features (or Control Panel, Uninstall a program depending on your view setting).
2. Click Turn Windows features on or off.
3. In the window that appears, click .NET Framework 3.5 (includes and 3.0) to expand it.
4. Checkmark the following options, which will auto checkmark the parent .NET 3.5 selection:
   • Windows Communication Foundation HTTP Activation
   • Windows Communication Foundation non-HTTP Activation
5. Click OK. Windows will search for required files, or specifically, for Windows source files. This can take a few minutes. One of two things will happen:
   1. If Windows finds the local source files (or original Windows 8 install files), Windows finalizes the .NET installation. Click Close to exit. Skip the remaining steps on this article.
   2. If Windows doesn’t find local source files, it prompts you to download required files from Windows Update. Click Download files from Windows Update.
6. Windows will download the required files and finalize the installation of .NET 3.5. This can take a few minutes. Click Close to exit.

To enable .NET 3.5 SP1 on a flavor of a Windows Server 2012 operating system, perform the following steps:

1. Open Control Panel, Program and Features (or Control Panel, Uninstall a program depending on your view setting).
2. Click Turn Windows features on or off.
3. The Add Roles and Features Wizard window opens. Review this information first.
4. After reviewing the information, click Next.
5. In the next few windows, the customer must review the options and decide which to choose. If the customer is unsure, on the Select installation type screen, select Role-based or feature-based installation. After clicking Next a few times, you’ll come to the Select Features page.
6. In the Select Features page, click the triangle icon next to .NET Framework 3.5 Features to expand it. Checkmark the following options below. If the Add Roles and Features Window appears, click Add Features.
   • NET Framework 3.5 (includes .NET 2.0 and 3.0)
   • HTTP Activation
   • Non-HTTP Activation
7. After checking the above selections, click Next.
8. Continue to make selections and read the confirmations. Click Next a few times until you reach the Confirm installation selections page.
9. On the Confirm installation selections page, verify .NET 3.5 features are on the list. You have two options:
   1. If you believe source files for Server 2012 are on the local computer, or if you’re unsure, click Install.
   2. If source files for Server 2012 aren’t on the local computer, click Specify an alternate source path. Enter a location for the source files and then click Install.
10. If the .NET 3.5 features install successfully, you'll see a message confirming the installation.
11. Close out of the Control Panel.

For the automatic downloads to complete properly, your company policy must allow you to download files from the Microsoft website. If you
receive an error message, click Tell me how to solve this problem or log unto Microsoft's website and review Microsoft knowledgebase
article number KB2734782, titled .NET Framework 3.5 installation error: 0x800F0906, 0x800F081F, 0x800F0907.

Note: Alternatively, instead of going through the Control Panel, you can use this command line to enable .NET 3.5. However, this option can cause the .NET components to not all install properly even if you received the message that it was successful. Verify in the Turn Windows features on or off screen that .NET 3.5 and its required components installed successfully. Confirm the ":d:" part corresponds to the DVD drive letter location of the Windows 8 or Server 2012 media.

dism /online /enable-feature /featurename:NetFX3 /all /Source:d:\sources\sxs /LimitAccess

For more information, see these Microsoft articles and links:

• How to enable .NET Framework 3.5 on Windows 8 in Offline Mode (Microsoft KB 2785188)
• Enable .NET Framework 3.5 by using the Add Roles and Features Wizard (Windows Server 2012 only)