When using Visual Studio Enterprise 16.3.7 on two separate machines one builds fine and the other machine throws the error.

Feature 'using declarations' is not available in C# 7.3. Please use language version 8.0 or greater.

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This can easily be solved on the none working machine by setting LangVersion in .csproj as suggested here https://stackoverflow.com/a/48085575/3850405 or let Visual Studio automatically fix it like the print screen above.


What I can't understand is why one machine builds fine without this line in .csproj and the other machine needs it?

Best Answer

I received the same error, but I had simply forgotten to include the


attribute in ALL the .csproj files in the solution. The following is my current c# 8 setup:


I found the following documents to be the most helpful when migrating from core 2.2 to 3.x.

MSDN 2.2 -> 3.0

MSDN 3.0 -> 3.1