diff --git a/functionaltests/api/v1/test_mistral_basic.py b/functionaltests/api/v1/test_mistral_basic.py
index f95cc9812..91b22fe2b 100644
--- a/functionaltests/api/v1/test_mistral_basic.py
+++ b/functionaltests/api/v1/test_mistral_basic.py
@@ -15,7 +15,6 @@
 # under the License.
 
 import json
-import testtools
 import uuid
 
 from tempest import exceptions
@@ -203,7 +202,6 @@ class AdvancedTests(base.TestCaseAdvanced):
         self.assertRaises(exceptions.NotFound, self.client.update_execution,
                           'test123', id, put_body)
 
-    @testtools.skip('https://bugs.launchpad.net/mistral/+bug/1326287')
     @test.attr(type='negative')
     def test_get_tasks_list_of_nonexistent_execution(self):
 
@@ -218,7 +216,6 @@ class AdvancedNegativeTestsWithExecutionCreate(base.TestCaseAdvanced):
 
         self.execution = self._create_execution('test123', 'aloha')[1]
 
-    @testtools.skip('https://bugs.launchpad.net/mistral/+bug/1326278')
     @test.attr(type='negative')
     def test_get_nonexistent_task(self):
         self.assertRaises(exceptions.NotFound, self.client.get_task,
diff --git a/mistral/api/controllers/v1/task.py b/mistral/api/controllers/v1/task.py
index 7dafce701..e1aa4de4c 100644
--- a/mistral/api/controllers/v1/task.py
+++ b/mistral/api/controllers/v1/task.py
@@ -114,9 +114,12 @@ class TasksController(rest.RestController):
 
             return Task.from_dict(values)
 
+    @rest_utils.wrap_wsme_controller_exception
     @wsme_pecan.wsexpose(Tasks, wtypes.text, wtypes.text)
     def get_all(self, workbook_name, execution_id):
         """Return all tasks within the execution."""
+        db_api.ensure_execution_exists(workbook_name, execution_id)
+
         LOG.debug("Fetch tasks [workbook_name=%s, execution_id=%s]" %
                   (workbook_name, execution_id))
 
diff --git a/mistral/db/api.py b/mistral/db/api.py
index 7efa91014..fa54a2060 100644
--- a/mistral/db/api.py
+++ b/mistral/db/api.py
@@ -98,6 +98,10 @@ def execution_get(workbook_name, id):
     return IMPL.execution_get(workbook_name, id)
 
 
+def ensure_execution_exists(workbook_name, execution_id):
+    return IMPL.ensure_execution_exists(workbook_name, execution_id)
+
+
 def execution_create(workbook_name, values):
     return IMPL.execution_create(workbook_name, values)
 
diff --git a/mistral/db/sqlalchemy/api.py b/mistral/db/sqlalchemy/api.py
index 2af3d30ab..7255cf752 100644
--- a/mistral/db/sqlalchemy/api.py
+++ b/mistral/db/sqlalchemy/api.py
@@ -405,6 +405,10 @@ def execution_get(workbook_name, execution_id):
     return execution
 
 
+def ensure_execution_exists(workbook_name, execution_id):
+    execution_get(workbook_name, execution_id)
+
+
 @to_dict
 def executions_get_all(**kwargs):
     return _executions_get_all(**kwargs)
diff --git a/mistral/tests/api/v1/controllers/test_tasks.py b/mistral/tests/api/v1/controllers/test_tasks.py
index ccee35e28..88182a750 100644
--- a/mistral/tests/api/v1/controllers/test_tasks.py
+++ b/mistral/tests/api/v1/controllers/test_tasks.py
@@ -85,6 +85,8 @@ class TestTasksController(base.FunctionalTest):
 
     @mock.patch.object(db_api, "tasks_get",
                        mock.MagicMock(return_value=TASKS))
+    @mock.patch.object(db_api, "ensure_execution_exists",
+                       mock.MagicMock(return_value={'id': "abc123"}))
     def test_get_all(self):
         resp = self.app.get('/v1/workbooks/my_workbook/executions/123/tasks')
 
@@ -92,3 +94,8 @@ class TestTasksController(base.FunctionalTest):
 
         self.assertEqual(len(resp.json), 1)
         self.assertDictEqual(TASKS[0], canonize(resp.json['tasks'][0]))
+
+    @mock.patch.object(db_api, "tasks_get",
+                       mock.MagicMock(return_value=TASKS))
+    def test_get_all_nonexistent_execution(self):
+        self.assertNotFound('/v1/workbooks/my_workbook/executions/123/tasks')