Business process error when executed from a background operation

Hello,

I am creating a service that calls a number of actions. It passes to the methods the required parameters and a userConnection. I pass the UserConnection to the service class using dependency injection:
 

public class MonitoringService : IMonitoringService
   {
       private UserConnection _userConnection;
 
 
       public MonitoringService(UserConnection userConnection)
       {
           _userConnection = userConnection;         
       }
// the rest of the code here
 
}
 

this service is run in the background declaring an implementation of creatio's IBackgroundTask and  IUserConnectionRequired interfaces. 

The actions are executed in parallel, as shown in the code below:

 public void ExecuteStepsAsync(
    Dictionary<Guid, BlockStepExecution> allSteps,
    BlockExecution blockExecution,
    Guid applicationId,
    Guid appFormId,
    IAppProduct product = null,
    DateTime? requestStartTime = null)
{
    var processors = Environment.ProcessorCount;
    var steps = blockExecution.Steps;
    var workQueue = new Queue<BlockStepExecution>(
        steps.Values.Where(step => step.IsReady(allSteps)).ToList()
        );
 
    while (workQueue.Count > 0)
    {
        var currentBatch = DequeueBatch(workQueue);
        var newSteps = new ConcurrentQueue<BlockStepExecution>();
 
        Parallel.ForEach(currentBatch, new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount }, step =>
        {
            StartStepExecution(step, requestStartTime);
 
            try
            {
                Execute(step, applicationId, appFormId, product);
                step.Complete();
            }
            catch (Exception ex)
            {
                step.Fail($"FAILED: {ex.Message}");
            }
 
            StepExecutionFinished(step);
 
            var followUp = step.GetConditionalFollowUp(steps.Values);
            if (followUp != null)
                newSteps.Enqueue(followUp);
        });
 
        foreach (var next in steps.Values.Where(s => s.IsReady(allSteps)))
            workQueue.Enqueue(next);
 
        while (newSteps.TryDequeue(out var child))
            workQueue.Enqueue(child);
        //if (!workQueue.Contains(child))
    }
}

and the method for action execution:

       

public void Execute(BlockStepExecution step, Guid applicationId, Guid appFormId, IAppProduct product)
       {
           if (step.ShouldSkipStep())
           {
               Logger.Info($"Step '{step.FZName}' skipped (ends with '-001').");
               return;
           }
           var action = _methodRegistry.GetAction(step.FZName);
           if (action == null)
               throw new NotImplementedException($"Step not implemented: {step.FZName}");
 
           action(applicationId, appFormId, product, _userConnection);            
       }

Some of the actions that are executed in parallel, call business processes. 

In some executions of the business processes I have encountered 2 errors:
 

and 

I think the problem is related to a connection that should be closed but is not and is reused in the next processes.

What could be the cause for these errors and how can I fix this issue?

Thank you in advance!