diff --git a/mistral/engine/actions.py b/mistral/engine/actions.py
index 602e5ddbc..2f11d5892 100644
--- a/mistral/engine/actions.py
+++ b/mistral/engine/actions.py
@@ -361,9 +361,16 @@ class AdHocAction(PythonAction):
                  wf_ctx=None):
         self.action_spec = spec_parser.get_action_spec(action_def.spec)
 
-        base_action_def = db_api.get_action_definition(
-            self.action_spec.get_base()
-        )
+        try:
+            base_action_def = db_api.get_action_definition(
+                self.action_spec.get_base()
+            )
+        except exc.DBEntityNotFoundError:
+            raise exc.InvalidActionException(
+                "Failed to find action [action_name=%s]" %
+                self.action_spec.get_base()
+            )
+
         base_action_def = self._gather_base_actions(
             action_def, base_action_def
         )
@@ -477,7 +484,12 @@ class AdHocAction(PythonAction):
             self.adhoc_action_defs.append(base)
 
             base_name = base.spec['base']
-            base = db_api.get_action_definition(base_name)
+            try:
+                base = db_api.get_action_definition(base_name)
+            except exc.DBEntityNotFoundError:
+                raise exc.InvalidActionException(
+                    "Failed to find action [action_name=%s]" % base_name
+                )
 
         # if the action is repeated
         if base.name in action_names:
diff --git a/mistral/tests/unit/engine/test_adhoc_actions.py b/mistral/tests/unit/engine/test_adhoc_actions.py
index a8f0c051e..713026c84 100644
--- a/mistral/tests/unit/engine/test_adhoc_actions.py
+++ b/mistral/tests/unit/engine/test_adhoc_actions.py
@@ -55,6 +55,16 @@ actions:
     output:
       nested_concat: '{{ _ }}'
 
+  missing_base:
+    base: wrong
+    input:
+      - some_input
+
+  nested_missing_base:
+    base: missing_base
+    input:
+      - some_input
+
 workflows:
   wf1:
     type: direct
@@ -118,6 +128,32 @@ workflows:
         action: nested_concat
         publish:
           nested_result: '{{ task().result }}'
+
+  wf6:
+    type: direct
+    output:
+      workflow_result: '{{ _.missing_result }}'
+    tasks:
+      missing_action:
+        action: missing_base
+        on-complete:
+          - next_action
+      next_action:
+        publish:
+          missing_result: 'Finished'
+
+  wf7:
+    type: direct
+    output:
+      workflow_result: '{{ _.missing_result }}'
+    tasks:
+      nested_missing_action:
+        action: nested_missing_base
+        on-complete:
+          - next_action
+      next_action:
+        publish:
+          missing_result: 'Finished'
 """
 
 
@@ -205,3 +241,32 @@ class AdhocActionsTest(base.EngineTestCase):
                 },
                 wf_ex.output
             )
+
+    def test_missing_adhoc_action_definition(self):
+        wf_ex = self.engine.start_workflow(
+            'my_wb.wf6', '')
+        self.await_workflow_error(wf_ex.id)
+        with db_api.transaction():
+            # Note: We need to reread execution to access related tasks.
+            wf_ex = db_api.get_workflow_execution(wf_ex.id)
+
+            tasks = wf_ex.task_executions
+
+            task1 = self._assert_single_item(tasks, name='missing_action')
+
+        self.assertEqual(states.ERROR, task1.state)
+
+    def test_nested_missing_adhoc_action_definition(self):
+        wf_ex = self.engine.start_workflow(
+            'my_wb.wf7', '')
+        self.await_workflow_error(wf_ex.id)
+        with db_api.transaction():
+            # Note: We need to reread execution to access related tasks.
+            wf_ex = db_api.get_workflow_execution(wf_ex.id)
+
+            tasks = wf_ex.task_executions
+
+            task1 = self._assert_single_item(tasks,
+                                             name='nested_missing_action')
+
+        self.assertEqual(states.ERROR, task1.state)
diff --git a/mistral/tests/unit/engine/test_run_action.py b/mistral/tests/unit/engine/test_run_action.py
index bb87b72ee..040ab4412 100644
--- a/mistral/tests/unit/engine/test_run_action.py
+++ b/mistral/tests/unit/engine/test_run_action.py
@@ -72,6 +72,11 @@ class RunActionEngineTest(base.EngineTestCase):
           input:
             - some_input
 
+        nested_missing_base:
+          base: missing_base
+          input:
+            - some_input
+
         loop_action:
           base: loop_action
           base-input:
@@ -235,12 +240,21 @@ class RunActionEngineTest(base.EngineTestCase):
     def test_run_action_with_missing_base(self):
         # Start action and see the result.
         self.assertRaises(
-            exc.DBEntityNotFoundError,
+            exc.InvalidActionException,
             self.engine.start_action,
             'missing_base',
             {'some_input': 'Hi'}
         )
 
+    def test_run_action_with_missing_nested_base(self):
+        # Start action and see the result.
+        self.assertRaises(
+            exc.InvalidActionException,
+            self.engine.start_action,
+            'nested_missing_base',
+            {'some_input': 'Hi'}
+        )
+
     def test_run_loop_action(self):
         # Start action and see the result.
         self.assertRaises(