A second operation starte d on this context before a previous operation completed

• Abp package version 4.5.0.
• .Net Core2.2. I use a timer at the reference layer to collect some serial port data and then use the event bus to process the data.Now I find that the program runs for a while and occasionally has a problem:

Unhandled Exception: System.InvalidOperationException: A second operation starte d on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext, however instance memb ers are not guaranteed to be thread safe. This could also be caused by a nested query being evaluated on the client, if this is the case rewrite the query avoid ing nested invocations. at Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.EnterCriticalSe ction() at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveCha nges(IReadOnlyList1 entriesToSave) at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveCha nges(Boolean acceptAllChangesOnSuccess) at Microsoft.EntityFrameworkCore.DbContext.SaveChanges(Boolean acceptAllChang esOnSuccess) at Abp.EntityFrameworkCore.AbpDbContext.SaveChanges() at Abp.Zero.EntityFrameworkCore.AbpZeroCommonDbContext3.SaveChanges() at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.SaveChangesInDbContext(DbCont ext dbContext) at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.SaveChanges() at Abp.EntityFrameworkCore.AbpDbContext.SaveChanges() at Abp.Zero.EntityFrameworkCore.AbpZeroCommonDbContext`3.SaveChanges() at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.SaveChangesInDbContext(DbCont ext dbContext) at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.SaveChanges() at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.CompleteUow() at Abp.Domain.Uow.UnitOfWorkBase.Complete() at Abp.Domain.Uow.UnitOfWorkInterceptor.PerformSyncUow(IInvocation invocation , UnitOfWorkOptions options) at Castle.DynamicProxy.AbstractInvocation.Proceed() at SensorBroker.Schedules.CompositeSensor.CompositeSensorCommunicatorHandler. OnParseData(Object state) in D:\SVN\VR-Code\Trunk\SensorBroker\Source\sensorbrok er-aspnet-core\src\SensorBroker.Application\Schedules\CompositeSensor\CompositeS ensorCommunicatorHandler.cs:line 144

[guaicaiboshi]

@guaicaiboshi Can you provide complete code to reproduce the problem? I’ll do a demo sometime

[ryancyq]

You can try using AsyncHelper.RunSync() instead of Wait()

AsyncHelper.RunSync(() => 
pressureSensorDataManager.AddOrUpdateSensorData(result) );