======  Install Error: .NET Framework 4.0 Required (Rhino 5 for Windows)  ======
> **Summary:** //The Rhino installer reports that the .NET 4.0 framework is required.//
> **Related installation help:** //[[/rhino/installproblems|Troubleshooting Rhino 5 Installation]]//

**Problem**

The Rhino 5 installer keeps asking for you to install .NET Framework 4, but .NET Framework 4 already exists on the system. Rhino 5 is not allowed to install.

**Cause** 

.NET Framework 4 is somehow broken on the system.

**Solution**
  - Download <color #999999>[[http://files.na.mcneel.com/misc/dotnetfx_cleanup_tool.zip|.NET Framework Cleanup tool]]</color>.
  - Run .NET Framework Cleanup tool.
  - Select **.NET Framework - All Versions** for the product to cleanup.\\ {{http://wiki.mcneel.com/_media/rhino/rhino5/k01521.png?w=405}}
  - Click the **Cleanup Now** button.\\ <color #999999>This takes some minutes to complete.</color>
  - If your computer does not reboot automatically, reboot.
  - Install Rhino 5 again.

**Note:** If this cleanup tool doesn't fix the problem, you can also try the [[http://wiki.mcneel.com/rhino/rhino5/dotnet4error|.NET Framework Repair tool]].

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