diff --git a/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs b/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
index 1e3c080f4..882dda36c 100644
--- a/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
+++ b/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
@@ -1,4 +1,6 @@
 using System.Runtime.CompilerServices;
+using System.Text.Json;
+using System.Text.Json.Nodes;
 using Elsa.Expressions.Helpers;
 using Elsa.Extensions;
 using Elsa.Workflows.Attributes;
@@ -42,8 +44,8 @@ public class ParallelForEach<T> : Activity
         var tags = new List<Guid>();
         var currentIndex = 0;
         
-        context.SetProperty(ScheduledTagsProperty, tags);
-        context.SetProperty(CompletedTagsProperty, new List<Guid>());
+        SetTagList(context, ScheduledTagsProperty, tags);
+        SetTagList(context, CompletedTagsProperty, new List<Guid>());
         
         await foreach (var item in items)
         {
@@ -51,10 +53,10 @@ public class ParallelForEach<T> : Activity
             var currentValueVariable = new Variable<T>("CurrentValue", item)
             {
                 // TODO: This should be configurable, because this won't work for e.g. file streams and other non-serializable types.
-                StorageDriverType = typeof(WorkflowStorageDriver)
+                StorageDriverType = typeof(WorkflowInstanceStorageDriver)
             };
 
-            var currentIndexVariable = new Variable<int>("CurrentIndex", currentIndex++) { StorageDriverType = typeof(WorkflowStorageDriver) };
+            var currentIndexVariable = new Variable<int>("CurrentIndex", currentIndex++) { StorageDriverType = typeof(WorkflowInstanceStorageDriver) };
             var variables = new List<Variable> { currentValueVariable, currentIndexVariable };
 
             // Schedule a body of work for each item.
@@ -71,15 +73,13 @@ public class ParallelForEach<T> : Activity
     private async ValueTask OnChildCompleted(ActivityCompletedContext context)
     {
         var targetContext = context.TargetContext;
-        var scheduledTags = targetContext.GetProperty<List<Guid>>(ScheduledTagsProperty)!;
+        var scheduledTags = GetTagList(targetContext, ScheduledTagsProperty);
         var completedTag = targetContext.Tag.ConvertTo<Guid>();
-
-        var completedTags = new HashSet<Guid>(targetContext.UpdateProperty<List<Guid>>(CompletedTagsProperty, completedTags =>
-        {
-            completedTags!.Add(completedTag);
-            return completedTags;
-        }));
-
+        var completedTags = GetTagList(targetContext, CompletedTagsProperty);
+        
+        completedTags.Add(completedTag);
+        SetTagList(targetContext, CompletedTagsProperty, completedTags);
+            
         // If not all scheduled activities have completed yet, we're not done yet.
         if (!scheduledTags.IsEqualTo(completedTags))
             return;
@@ -87,4 +87,18 @@ public class ParallelForEach<T> : Activity
         // We're done, so complete the activity.
         await targetContext.CompleteActivityAsync();
     }
+    
+    private ICollection<Guid> GetTagList(ActivityExecutionContext context, string propertyName)
+    {
+        // Read the list of tags from the context using the specified property name. The value is stored as JsonArray, so we need to deserialize it.
+        var jsonArray = context.GetProperty<JsonArray>(propertyName);
+        return jsonArray.Select(x => x.ConvertTo<Guid>()).ToList();
+    }
+    
+    private void SetTagList(ActivityExecutionContext context, string propertyName, ICollection<Guid> tags)
+    {
+        // Serialize the list of tags to a JsonArray and store it in the context using the specified property name.
+        var jsonArray = JsonSerializer.SerializeToNode(tags) as JsonArray;
+        context.SetProperty(propertyName, jsonArray);
+    }
 }
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