.Net Core

Question 1

Upgrade to .NET Core 3.1

Answer 1

Open the project file (the *.csproj, *.vbproj, or *.fsproj file).
Change the target framework value from netcoreapp3.0 to netcoreapp3.1. The target framework is defined by the or element.
For example, change netcoreapp3.0 to netcoreapp3.1.

Question 2

.Net 5

Answer 2

https://devblogs.microsoft.com/dotnet/announcing-net-5-0-preview-1/

High-level goals for .NET 5
Let me highlight some of the high-level goals for .NET 5:

Unified .NET SDK experience:
Single BCL (Base Class Library) across all .NET 5 applications. Today Xamarin applications use the Mono BCL but will move to use the.NET Core BCL, improving compatibility across our application models.
Mobile development (Xamarin) is integrated into .NET 5. This means the .NET SDK will support mobile. For example, you can use “dotnet new XamarinForms” to create a mobile application.
Native Applications supporting multiple platforms: Single Device project that supports an application that can work across multiple devices for example Window Desktop, Microsoft Duo (Android), and iOS using the native controls supported on those platforms.
Web Applications supporting multiple platforms: Single Blazor project that supports an application that can work in browsers, on mobile devices and as a native desktop application (Windows 10x for example)
Cloud Native Applications: High performance, single file (.exe) <50MB microservices and support for building multiple project (API, web front ends, containers) both locally and in the cloud.
Continuous Improvements, such as: faster algorithms in the BCL, better support for containers in the runtime, support for HTTP3.