diff --git a/source/java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessor.java b/source/java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessor.java
index dc31e8ef5f..60c0fb98ba 100644
--- a/source/java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessor.java
+++ b/source/java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessor.java
@@ -107,7 +107,13 @@ public class TaskFormProcessor extends AbstractWorkflowFormProcessor<WorkflowTas
     @Override
     protected WorkflowTask getTypedItemForDecodedId(String itemId)
     {
-        return workflowService.getTaskById(itemId);
+        WorkflowTask task = workflowService.getTaskById(itemId);
+        if (task == null)
+        {
+            String msg = "Workflow task does not exist: " + itemId;
+            throw new IllegalArgumentException(msg);
+        }
+        return task;
     }
 
     /**
diff --git a/source/test-java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessorTest.java b/source/test-java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessorTest.java
index fd7461ae16..a298e5d4dc 100644
--- a/source/test-java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessorTest.java
+++ b/source/test-java/org/alfresco/repo/forms/processor/workflow/TaskFormProcessorTest.java
@@ -57,7 +57,6 @@ import org.alfresco.service.cmr.repository.NodeService;
 import org.alfresco.service.cmr.security.AuthenticationService;
 import org.alfresco.service.cmr.security.PersonService;
 import org.alfresco.service.cmr.workflow.WorkflowDefinition;
-import org.alfresco.service.cmr.workflow.WorkflowException;
 import org.alfresco.service.cmr.workflow.WorkflowInstance;
 import org.alfresco.service.cmr.workflow.WorkflowNode;
 import org.alfresco.service.cmr.workflow.WorkflowPath;
@@ -787,7 +786,10 @@ public class TaskFormProcessorTest extends TestCase
                 if (TASK_ID.equals(id))
                     return task;
                 else
-                    throw new WorkflowException("Task Id not found!");
+                {
+                    // if TaskId is not found then Activity returns null, does not throws WorkflowException
+                    return null;
+                }
             }
         });