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.
This can easily be solved on the none working machine by setting
.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?
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:
<PropertyGroup> <TargetFramework>netcoreapp3.1</TargetFramework> <LangVersion>8.0</LangVersion> <Nullable>enable</Nullable> <NullableContextOptions>enable</NullableContextOptions> </PropertyGroup>
I found the following documents to be the most helpful when migrating from core 2.2 to 3.x.