diff --git a/dotflow/core/context.py b/dotflow/core/context.py
index 087a1d04..66541047 100644
--- a/dotflow/core/context.py
+++ b/dotflow/core/context.py
@@ -80,6 +80,13 @@ def workflow_id(self):
 
     @workflow_id.setter
     def workflow_id(self, value: UUID):
+        if isinstance(value, str):
+            try:
+                value = UUID(value)
+            except ValueError as err:
+                raise ValueError(
+                    f"Invalid workflow_id: '{value}' is not a valid UUID format."
+                ) from err
         if isinstance(value, UUID):
             self._workflow_id = value
 
diff --git a/dotflow/core/execution.py b/dotflow/core/execution.py
index 3eadaf00..98b46859 100644
--- a/dotflow/core/execution.py
+++ b/dotflow/core/execution.py
@@ -59,7 +59,7 @@ def _is_action(self, class_instance: Callable, func: Callable):
             return (
                 callable(getattr(class_instance, func))
                 and getattr(class_instance, func).__module__
-                is Action.__module__
+                == Action.__module__
                 and not func.startswith("__")
             )
         except AttributeError:
diff --git a/dotflow/core/module.py b/dotflow/core/module.py
index 0866c16c..2297bf97 100644
--- a/dotflow/core/module.py
+++ b/dotflow/core/module.py
@@ -19,7 +19,7 @@ def import_module(cls, value: str):
         spec = file_location(value, cls._get_path(value))
         module = module_from_spec(spec)
 
-        sys.modules[module] = module
+        sys.modules[module.__name__] = module
         spec.loader.exec_module(module)
 
         if hasattr(module, cls._get_name(value)):
diff --git a/dotflow/core/workflow.py b/dotflow/core/workflow.py
index 5e7b9bab..312275ce 100644
--- a/dotflow/core/workflow.py
+++ b/dotflow/core/workflow.py
@@ -107,10 +107,16 @@ def __init__(
         execution = None
         groups = grouper(tasks=tasks)
 
-        try:
-            execution = getattr(self, mode)
-        except AttributeError as err:
-            raise ExecutionModeNotExist() from err
+        VALID_MODES = {
+            "sequential",
+            "sequential_group",
+            "background",
+            "parallel",
+        }
+        if mode not in VALID_MODES:
+            raise ExecutionModeNotExist()
+
+        execution = getattr(self, mode)
 
         self.tasks = execution(
             tasks=tasks,