diff --git a/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeBulkDispatchWorkflowActivity.cs b/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeBulkDispatchWorkflowActivity.cs
index 7532d376e..5c95a13a4 100644
--- a/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeBulkDispatchWorkflowActivity.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeBulkDispatchWorkflowActivity.cs
@@ -26,7 +26,10 @@ internal class ResumeBulkDispatchWorkflowActivity(IBookmarkQueue bookmarkQueue,
         if (!waitForCompletion)
             return;
         
-        var parentInstanceId = (string)workflowState.Properties["ParentInstanceId"];
+        if (!workflowState.Properties.TryGetValue("ParentInstanceId", out var parentInstanceIdValue))
+            return;
+        
+        var parentInstanceId = (string)parentInstanceIdValue;
         var activityTypeName = ActivityTypeNameHelper.GenerateTypeName<BulkDispatchWorkflows>();
         var stimulus = new BulkDispatchWorkflowsStimulus(parentInstanceId);
         var stimulusHash = stimulusHasher.Hash(activityTypeName, stimulus);
diff --git a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs
index 96fb810be..2a13ec262 100644
--- a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs
+++ b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs
@@ -36,6 +36,9 @@ public class DeleteWorkflowTests : AppComponentTest
         var workflowDefinitionManager = _scope1.ServiceProvider.GetRequiredService<IWorkflowDefinitionManager>();
         await workflowDefinitionManager.DeleteByDefinitionIdAsync(Workflows.DeleteWorkflow.DefinitionId);
 
+        // Wait for the event handler to process the deletion from the activity registry
+        await _signalManager.WaitAsync(WorkflowDeletedSignal, 5000);
+
         WorkflowTypeDeletedFromRegistry(_scope1, Workflows.DeleteWorkflow.Type);
     }