title: Error constructing handler for request of type mediatr.irequesthandler`2
body: <p>This problem occurred when I inject <strong>IMapper</strong> into the MediatR command handler. I injected properly before this happen but after that changed <strong>AutoMapper</strong> and <strong>MediatR</strong> configs like bellow. (I added all assemblies of application layers)</p>
  <pre><code>services.AddAutoMapper(Assembly.GetExecutingAssembly(),
                                 typeof(CreateAccountCommand).Assembly,
                                 typeof(EfRepository&lt;,&gt;).Assembly,
                                 typeof(IRepository&lt;,&gt;).Assembly,
                                 typeof(KeyValueDto).Assembly);
  
          services.AddMediatR(Assembly.GetExecutingAssembly(),
                              typeof(CreateAccountCommand).Assembly,
                              typeof(EfRepository&lt;,&gt;).Assembly,
                              typeof(IRepository&lt;,&gt;).Assembly,
                              typeof(KeyValueDto).Assembly);
  </code></pre>
  <p>When I execute <strong>CreateAccountCommand</strong> the error occures like bellow:</p>
  <pre><code>Error constructing handler for request of type MediatR.IRequestHandler`2[Application.Actions.Users.Commands.CreateAccountCommand,Application.Common.Models.GenericResponse`1[System.String]]. Register your handlers with the container. See the samples in GitHub for examples.
  </code></pre>
  <p>Inner exception is bellow</p>
  <pre><code>Property 'System.Linq.IQueryable`1[Domain.Entities.Thumbnail] Thumbnails' is not defined for type 'Domain.Entities.Thumbnail' (Parameter 'property')
  </code></pre>