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ViewsFeature 'using declarations' is not available in C# 7.3. Please use language version 8.0 or greater - Error on one machine but works on another
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.
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.
<LangVersion>8.0</LangVersion>
What I can't understand is why one machine builds fine without this line in .csproj and the other machine needs it?
2 answers
Answer question0
I received the same error, but I had simply forgotten to include the
<LangVersion>8.0</LangVersion>
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:
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I had to update Visual Studio to version from 16.3.X to 16.4.2. This resolved the problem and I didn't have to add any LangVersion.
Credits: https://github.com/aspnet/AspNetCore.Docs/issues/16047