Object reference not set to an instance of an object (Entity History)

Abp package version.: 3.4.0 base framework: .Net Framework Exception:

System.NullReferenceException
  HResult=0x80004003
  Message=Object reference not set to an instance of an object.
  Source=Microsoft.AspNetCore.Http.Extensions
  StackTrace:
   at Microsoft.AspNetCore.Http.Extensions.UriHelper.GetDisplayUrl(HttpRequest request)
   at Abp.AspNetCore.EntityHistory.HttpRequestEntityChangeSetReasonProvider.get_Reason()
   at Abp.EntityHistory.EntityHistoryHelper.CreateEntityChangeSet(ICollection`1 entityEntries)
   at Abp.Zero.EntityFrameworkCore.AbpZeroCommonDbContext`3.<SaveChangesAsync>d__98.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.<SaveChangesInDbContextAsync>d__20.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.<SaveChangesAsync>d__12.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.<CompleteUowAsync>d__14.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Abp.Domain.Uow.UnitOfWorkBase.<CompleteAsync>d__57.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Abp.Domain.Uow.UnitOfWorkInterceptor.<>c__DisplayClass6_0.<<PerformAsyncUow>b__2>d.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Abp.Threading.InternalAsyncHelper.<AwaitTaskWithPostActionAndFinallyAndGetResult>d__5`1.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at SystemX.X.Reports.DetailedBankSalaryTransferReport.<>c__DisplayClass8_0.<<DetailedBankSalaryTransferReport_NeedDataSource>b__0>d.MoveNext() in D:\Work\src\SystemX System\src\X\SystemX.X.Reports\DetailedBankSalaryTransferReport.cs:line 44
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Nito.AsyncEx.Synchronous.TaskExtensions.WaitAndUnwrapException[TResult](Task`1 task)
   at Nito.AsyncEx.AsyncContext.<>c__DisplayClass16_0`1.<Run>b__0(Task`1 t)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Nito.AsyncEx.Synchronous.TaskExtensions.WaitAndUnwrapException[TResult](Task`1 task)
   at Nito.AsyncEx.AsyncContext.Run[TResult](Func`1 action)
   at Abp.Threading.AsyncHelper.RunSync[TResult](Func`1 func)
   at SystemX.X.Reports.DetailedBankSalaryTransferReport.DetailedBankSalaryTransferReport_NeedDataSource(Object sender, EventArgs e) in D:\Work\src\SystemX System\src\X\SystemX.X.Reports\DetailedBankSalaryTransferReport.cs:line 43
   at Telerik.Reporting.Report.OnNeedDataSource(Object sender, EventArgs e)
   at Telerik.Reporting.Report.RaiseNeedDataSource(Object sender, EventArgs e)
   at Telerik.Reporting.Processing.Report.ResolveDataSourceDefinition(Report definition)
   at Telerik.Reporting.Processing.Report.<>c__DisplayClassd.<ResolveData>b__c()
   at Telerik.Reporting.Processing.DataItemResolveDataAlgorithm.ResolveData(String processingId, InMemoryState inMemoryState, MultidimensionalQuery query, Func`1 getDataCore, EvalObject expressionContext)
   at Telerik.Reporting.Processing.Report.ResolveData()
   at Telerik.Reporting.Processing.Report.ProcessItemCore()
   at Telerik.Reporting.Processing.Report.ProcessItem()
   at Telerik.Reporting.Processing.ReportItemBase.ProcessElement()
   at Telerik.Reporting.Processing.Report.ProcessElement()
   at Telerik.Reporting.Processing.ProcessingElement.Process(IDataMember dataContext)

I feel this is happening because Telerik is using second thread to some job with the report and this second thread doesn’t have AbpSession and also doesn’t have HttpRequest and so it has this issue. Edit: I tried to disable the EntityHistory using this

Configuration.EntityHistory.IsEnabled = false;

But it has no effect.

[ismcagdas]

@iyhammad even if you disable EntityHistory, AbpSession is used here https://github.com/aspnetboilerplate/aspnetboilerplate/blob/master/src/Abp.ZeroCore.EntityFrameworkCore/EntityHistory/EntityHistoryHelper.cs#L69.

So, as a temporary workaround, you can override CreateEntityChangeSet method of EntityHistoryHelper.

@acjh should we check if AbpSession is null or not ? An EntityHistory record might be created by a windows service or an app without a user. What do you think ?

[ismcagdas]

@easyest could you share the full stack-trace ?