diff --git a/tests/test_test_api_adapter.py b/tests/test_test_api_adapter.py
index d12acf3..385474f 100644
--- a/tests/test_test_api_adapter.py
+++ b/tests/test_test_api_adapter.py
@@ -114,7 +114,7 @@ def test_set_running_workflow_done_when_success():
     response, _ = utaa.get_running_workflow(running_workflow_id=rwfid)
     assert response["done"]
     assert response["success"]
-    assert response["error"] is None
+    assert response["error_num"] is None
     assert response["error_msg"] is None
 
 
@@ -132,14 +132,14 @@ def test_set_running_workflow_done_when_failed():
 
     # Act
     utaa.set_running_workflow_done(
-        running_workflow_id=rwfid, success=False, error=1, error_msg="Bang!"
+        running_workflow_id=rwfid, success=False, error_num=1, error_msg="Bang!"
     )
 
     # Assert
     response, _ = utaa.get_running_workflow(running_workflow_id=rwfid)
     assert response["done"]
     assert not response["success"]
-    assert response["error"] == 1
+    assert response["error_num"] == 1
     assert response["error_msg"] == "Bang!"
 
 
@@ -210,7 +210,7 @@ def test_set_running_workflow_step_done_when_success():
     response, _ = utaa.get_running_workflow_step(running_workflow_step_id=rwfsid)
     assert response["done"]
     assert response["success"]
-    assert response["error"] is None
+    assert response["error_num"] is None
     assert response["error_msg"] is None
     assert response["variables"] == {}
 
@@ -232,14 +232,14 @@ def test_set_running_workflow_step_done_when_failed():
 
     # Act
     utaa.set_running_workflow_step_done(
-        running_workflow_step_id=rwfsid, success=False, error=1, error_msg="Bang!"
+        running_workflow_step_id=rwfsid, success=False, error_num=1, error_msg="Bang!"
     )
 
     # Assert
     response, _ = utaa.get_running_workflow_step(running_workflow_step_id=rwfsid)
     assert response["done"]
     assert not response["success"]
-    assert response["error"] == 1
+    assert response["error_num"] == 1
     assert response["error_msg"] == "Bang!"
 
 
diff --git a/tests/wapi_adapter.py b/tests/wapi_adapter.py
index 770f588..23f7cbd 100644
--- a/tests/wapi_adapter.py
+++ b/tests/wapi_adapter.py
@@ -105,7 +105,7 @@ def set_running_workflow_done(
         *,
         running_workflow_id: str,
         success: bool,
-        error: int | None = None,
+        error_num: int | None = None,
         error_msg: str | None = None,
     ) -> None:
         UnitTestWorkflowAPIAdapter.lock.acquire()
@@ -115,7 +115,7 @@ def set_running_workflow_done(
         assert running_workflow_id in running_workflow
         running_workflow[running_workflow_id]["done"] = True
         running_workflow[running_workflow_id]["success"] = success
-        running_workflow[running_workflow_id]["error"] = error
+        running_workflow[running_workflow_id]["error_num"] = error_num
         running_workflow[running_workflow_id]["error_msg"] = error_msg
 
         with open(_RUNNING_WORKFLOW_PICKLE_FILE, "wb") as pickle_file:
@@ -184,7 +184,7 @@ def set_running_workflow_step_done(
         *,
         running_workflow_step_id: str,
         success: bool,
-        error: int | None = None,
+        error_num: int | None = None,
         error_msg: str | None = None,
     ) -> None:
         UnitTestWorkflowAPIAdapter.lock.acquire()
@@ -194,7 +194,7 @@ def set_running_workflow_step_done(
         assert running_workflow_step_id in running_workflow_step
         running_workflow_step[running_workflow_step_id]["done"] = True
         running_workflow_step[running_workflow_step_id]["success"] = success
-        running_workflow_step[running_workflow_step_id]["error"] = error
+        running_workflow_step[running_workflow_step_id]["error_num"] = error_num
         running_workflow_step[running_workflow_step_id]["error_msg"] = error_msg
 
         with open(_RUNNING_WORKFLOW_STEP_PICKLE_FILE, "wb") as pickle_file:
diff --git a/workflow/workflow_abc.py b/workflow/workflow_abc.py
index 34489b6..1a1ff35 100644
--- a/workflow/workflow_abc.py
+++ b/workflow/workflow_abc.py
@@ -134,8 +134,8 @@ def get_running_workflow(
         #       "running_user_api_token": "123456789",
         #       "done": False,
         #       "success": false,
-        #       "error": None,
-        #       "error_msg": None,
+        #       "error_num": 0,
+        #       "error_msg": "",
         #       "workflow": {
         #          "id": "workflow-000",
         #       },
@@ -155,7 +155,7 @@ def set_running_workflow_done(
         *,
         running_workflow_id: str,
         success: bool,
-        error: int | None = None,
+        error_num: int | None = None,
         error_msg: str | None = None,
     ) -> None:
         """Set the success value for a RunningWorkflow Record.
@@ -184,8 +184,8 @@ def get_running_workflow_step(
         #       "name:": "step-1234",
         #       "done": False,
         #       "success": false,
-        #       "error": None,
-        #       "error_msg": None,
+        #       "error_num": 0,
+        #       "error_msg": "",
         #       "variables": {
         #          "x": 1,
         #          "y": 2,
@@ -213,7 +213,7 @@ def set_running_workflow_step_done(
         *,
         running_workflow_step_id: str,
         success: bool,
-        error: int | None = None,
+        error_num: int | None = None,
         error_msg: str | None = None,
     ) -> None:
         """Set the success value for a RunningWorkflowStep Record,
@@ -224,12 +224,7 @@ def get_instance(self, *, instance_id: str) -> tuple[dict[str, Any], int]:
         """Get an Instance Record"""
         # For a RunningWorkflowStep Instance it should return:
         # {
-        #    "id": "instance-00000000-0000-0000-0000-000000000001",
-        #    "running_workflow_step": {
-        #       "id": "r-workflow-step-00000000-0000-0000-0000-000000000001",
-        #       "step": "step-1234",
-        #    },
-        #    [...],
+        #    "running_workflow_step_id": "r-workflow-step-00000000-0000-0000-0000-000000000001",
         # }
         # If not present an empty dictionary should be returned.
 
diff --git a/workflow/workflow_engine.py b/workflow/workflow_engine.py
index bc7c285..535776a 100644
--- a/workflow/workflow_engine.py
+++ b/workflow/workflow_engine.py
@@ -438,13 +438,13 @@ def _set_step_error(
         self._wapi_adapter.set_running_workflow_step_done(
             running_workflow_step_id=r_wfsid,
             success=False,
-            error=error,
+            error_num=error,
             error_msg=error_msg,
         )
         # We must also set the running workflow as done (failed)
         self._wapi_adapter.set_running_workflow_done(
             running_workflow_id=r_wfid,
             success=False,
-            error=error,
+            error_num=error,
             error_msg=error_msg,
         )