Target older versions of .NET (F#)

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Applies to: yesVisual Studio noVisual Studio for Mac

Note

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The following error might appear if you try to target the .NET Framework 2.0, 3.0, or 3.5 in an F# project when Visual Studio is installed on Windows 8.1:

This project requires the 2.0 F# runtime, but that runtime is not installed.

This error is known to occur under the following combination of conditions:

  • You installed Visual Studio on Windows 8.1.

  • You didn’t enable the .NET Framework 3.5 before you installed Visual Studio.

  • Your project targets the .NET Framework 2.0, 3.0, or 3.5.

When you install Visual Studio, it detects the installed versions of the .NET Framework. Visual Studio installs the F# 2.0 runtime only if the .NET Framework 3.5 is installed and enabled.

Resolve the error

To resolve this error, you can either:

  • Target a newer version of the .NET Framework.

  • Enable the .NET Framework 3.5 on Windows 8.1 and then install the F# 2.0 runtime by repairing the Visual Studio installation. The steps to do this follow.

To enable the .NET Framework 3.5 on Windows 8.1

  1. On the Start screen, type Control Panel.

    As you type, the Control Panel icon appears under the Apps heading.

  2. Choose the Control Panel icon, choose the Programs icon, and then choose the Turn Windows features on or off link.

  3. Make sure that the .NET Framework 3.5 (includes .NET 2.0 and 3.0) check box is selected, and then choose the OK button. You don’t need to select the check boxes for any child nodes for optional components of the .NET Framework.

    The .NET Framework 3.5 is enabled if it wasn't already.

To install the F# 2.0 runtime

Follow the steps to repair Visual Studio.

See also