Object reference not set to an instance of an object.

[Yuval2612]

Describe the bug I'm using WorkFlowCore with asp.net core, at the end of each workflow I see in the log 'fail: WorkflowCore.Services.BackgroundTasks.WorkflowConsumer[0]' I look into it and saw that somehow the function GetWorkflowInstance was called and the workflows are empty. this function is located in the class that uses IPersistenceProvider.

To Reproduce Create a flow from JSON

Expected behavior The null exception should not appear.

Additional context example of the error log: fail: WorkflowCore.Services.BackgroundTasks.WorkflowConsumer[0] Error executing item 41b5ef64-ba42-4511-8ccc-7b78d65adc80 - Object reference not set to an instance of an object. System.NullReferenceException: Object reference not set to an instance of an object. at WorkflowCore.Services.BackgroundTasks.WorkflowConsumer.ProcessItem(String itemId, CancellationToken cancellationToken) at WorkflowCore.Services.BackgroundTasks.WorkflowConsumer.ProcessItem(String itemId, CancellationToken cancellationToken) at WorkflowCore.Services.BackgroundTasks.QueueConsumer.ExecuteItem(String itemId, EventWaitHandle waitHandle, Activity activity)

this is the JSON flow { "Id": "ny", "Version": 1, "DataType": "Getb.Evaluation.Flow.Manager.FlowExecution.FlowContext, Getb.Evaluation.Flow.Manager", "ErrorBehavior":"Terminate", "Steps": [ { "Id": "Initialization", "StepType": "Getb.Evaluation.Flow.Manager.Steps.Initialization, Getb.Evaluation.Flow.Manager", "ErrorBehavior":"Terminate", "NextStepId": "ParallelTracking" }, { "Id": "ParallelTracking", "StepType": "WorkflowCore.Primitives.Sequence, WorkflowCore", "ErrorBehavior":"Terminate", "NextStepId": "Evaluation", "Do": [ [ { "Id": "Tracking", "StepType": "Getb.Evaluation.Flow.Manager.Steps.Tracking, Getb.Evaluation.Flow.Manager", "ErrorBehavior":"Terminate", "Inputs": { "System": ""ny"", "IgnorePlots": ""py"" } } ] ] }, { "Id": "Evaluation", "StepType": "Retb.Evaluation.Flow.Manager.Steps.Evaluation, Retb.Evaluation.Flow.Manager", "ErrorBehavior":"Terminate", "NextStepId": "Finalization", "Inputs": { "System": ""ny"" } }, { "Id": "Finalization", "StepType": "Retb.Evaluation.Flow.Manager.Steps.Finalization, Retb.Evaluation.Flow.Manager", "ErrorBehavior":"Terminate" } ] }

[scccboom]

This is usually caused by incorrect persistence, and sometimes the workflow ends after it is started. You should provide more detailed information. For example persistence code, database

[eli-ilushin]

I've encountered a similar issue and it was caused because in some cases my implementation of IPersistenceProvider was returning null from GetWorkflowInstance(...)