I worked on a asp.net core 1.1 project a while ago and use in projetc AutoMapper.
in asp.net core 1.1, I add services.AddAutoMapper() in startup file :<
services.AddAutoMapper()
In new version (6.1) of AutoMapper.Extensions.Microsoft.DependencyInjection nuget package you should use it as follows:
AutoMapper.Extensions.Microsoft.DependencyInjection
services.AddAutoMapper(Type assemblyTypeToSearch); // OR services.AddAutoMapper(params Type[] assemblyTypesToSearch);
e.g:
services.AddAutoMapper(typeOf(yourClass));