Refer the below article to migrate ASP.NET Core 2.2 to 3.0
https://docs.microsoft.com/en-us/aspnet/core/migration/22-to-30
Refer the below article to migrate ASP.NET Core 2.1 to 2.2
https://docs.microsoft.com/en-us/aspnet/core/migration/21-to-22
Refer the below article to migrate ASP.NET Core 2.0 to 2.1
https://docs.microsoft.com/en-us/aspnet/core/migration/20_21
Refer the below article to migrate ASP.NET Core 1.x to 2.0
https://docs.microsoft.com/en-us/aspnet/core/migration/1x-to-2x
Refer the below article to migrate ASP.NET to ASP.NET Core
https://docs.microsoft.com/en-us/aspnet/core/migration/proper-to-2x/?view=aspnetcore-3.0