System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](List`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
at Nop.Web.Factories.CatalogModelFactory.<>c__DisplayClass37_0.<UpdatePrice>b__1()
at EasyCaching.InMemory.DefaultInMemoryCachingProvider.BaseGet[T](String cacheKey, Func`1 dataRetriever, TimeSpan expiration)
at EasyCaching.Core.EasyCachingAbstractProvider.Get[T](String cacheKey, Func`1 dataRetriever, TimeSpan expiration)
at Nop.Core.Caching.MemoryCacheManager.Get[T](String key, Func`1 acquire, Nullable`1 cacheTime)
at Nop.Web.Factories.CatalogModelFactory.UpdatePrice(IList`1 products)
at Nop.Web.Factories.CatalogModelFactory.PrepareCategoryModel(Category category, CatalogPagingFilteringModel command)
at Nop.Web.Controllers.CatalogController.Category(Int32 categoryId, CatalogPagingFilteringModel command)
at lambda_method(Closure , Object , Object[] )
at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
at WebMarkupMin.AspNetCore2.WebMarkupMinMiddleware.Invoke(HttpContext context)
at StackExchange.Profiling.MiniProfilerMiddleware.Invoke(HttpContext context) in C:\projects\dotnet\src\MiniProfiler.AspNetCore\MiniProfilerMiddleware.cs:line 94
at Nop.Services.Authentication.AuthenticationMiddleware.Invoke(HttpContext context) in C:\Users\lamwo\Websites\ITM Trading\4.20 Codes\Libraries\Nop.Services\Authentication\AuthenticationMiddleware.cs:line 79
at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
at Nop.Services.Installation.InstallUrlMiddleware.Invoke(HttpContext context, IWebHelper webHelper) in C:\Users\lamwo\Websites\ITM Trading\4.20 Codes\Libraries\Nop.Services\Installation\InstallUrlMiddleware.cs:line 52
at Nop.Services.Common.KeepAliveMiddleware.Invoke(HttpContext context, IWebHelper webHelper) in C:\Users\lamwo\Websites\ITM Trading\4.20 Codes\Libraries\Nop.Services\Common\KeepAliveMiddleware.cs:line 49
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw(Exception source)
at Nop.Web.Framework.Infrastructure.Extensions.ApplicationBuilderExtensions.<>c.<UseNopExceptionHandler>b__1_1(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)