Error: It was not possible to find any installed .NET Core SDKs

For me it happened when I had wrong ENTRYPOINT in my DOCKERFILE

# Build runtime image
FROM mcr.microsoft.com/dotnet/core/aspnet:3.1
WORKDIR /app
COPY --from=build-env /app/out .
ENTRYPOINT ["dotnet", "SampleAppForDocker.dll"]

Make sure that you run correct dll in your ENTRYPOINT. I had wrong name of dll file.