Error message

I am reviewing “Your First Script” in the " Complete C# Unity Game Developer 3D Online Course - 2020" and I get a notification of a Error. It has a pop up that says “Some projects have trouble loading. Please review the output for details.”

So I click on the “Show Output” button in the popup message which brings up the Debug section of the C# script program at the bottom of the coding page and it says:

i:\Unity2\Unity 3D\Experimenting\Assembly-CSharp.csproj

C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1177,5): Error: The reference assemblies for .NETFramework,Version=v4.7.1 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at

    Attempted to update project that is not loaded: i:\Unity2\Unity 3D\Experimenting\Assembly-CSharp.csproj

What does all that mean?

Hi Richard,

Have you already tried to restart Unity and Visual Studio?

The .NET Framework 4.7.1 is installed isn’t it? If I remember correctly, you have been a student of our courses for a while, so you probably didn’t get this error before. If so, there is probably an issue with Visual Studio. If restarting didn’t work, close Unity and VS. Then delete the .sln and .csproj files in your project folder, then start Unity again.

Okay, I will give this a try. Thanks :slight_smile:

I did delete the .sln and .csproj files and even restarted the computer to no avail. the message pops up when I start Visual Studio from the project by double clicking the C# file in the Unity program. It doesn’t seem to effect what the little program in this exercise is supposed to do so I am moving on in the course and keeping an eye on anything like this in future project folders.

Thanks for your help. It really is appreciated.

If you are able to write and use your code, ignore the message for now. If it appears again in your next project, please try to do what Csharpalos suggested in their answer (post #27):

If the issue persists, please let me know.

It has popped up on the start up of Visual Code a couple of times after I wrote the note. I have ignored it. I don’t think it came up on my screen today.

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