A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
at Bulev.Library.Products.BookmarksRepository.GetAsync(Sessions session) in C:\_projects\Eltedi.ru\Bulev.Library.Products\Repositories\BookmarksRepository.cs:line 56
at Bulev.Library.Products.BookmarksIM.ToActionResult(BaseController controller) in C:\_projects\Eltedi.ru\Bulev.Library.Products\Models\Bookmarks.cs:line 26