.Net Framework project complains about nullable not being supported in C# 7.3

I have a very old project my team is now working on and for some reason when I try to build it in VS 2022 I get the following error

Invalid 'nullable' value: 'Enable' for C# 7.3. Please use language version '8.0' or greater.

Invalid 'nullable' value: 'Enable' for C# 7.3. Please use language version '8.0' or greater.

Invalid 'nullable' value: 'Enable' for C# 7.3. Please use language version '8.0' or greater.

Invalid 'nullable' value: 'Enable' for C# 7.3. Please use language version '8.0' or greater.

There are two projects in here that use .net 6 and 7. Most projects are using net4.8 I checked the csproj files they don't have <Nullable>enable</Nullable>

The wierd thing is this is only happening on my machine. Any ideas on why VS thinks nullable is enabled on projects using net48. There is no Directory.Build.props file either.

reflectronic•4/2/25, 7:51 PM

does it happen when you use dotnet builddotnet build?

WarchortleOP•4/2/25, 7:58 PM

I don't think so. I can build it using our build.cake setup. Looking through it I don't see how its running the build though

WarchortleOP•4/2/25, 8:11 PM

just ran dotnet build it failed with the same errirs

reflectronic•4/2/25, 8:15 PM

to debug issues like this i would start with https://msbuildlog.com/

WarchortleOP•4/2/25, 8:22 PM

I see the error in the logviewer but not sure what to do with it

reflectronic•4/2/25, 11:33 PM

what do you see if you search for "LangVersion"

Angius•4/3/25, 3:05 AM

Do you maybe have a #nullable enable#nullable enable pragma anywhere?

.Net Framework project complains about nullable not being supported in C# 7.3

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