diff --git a/requirements.txt b/requirements.txt
index ab0cdd10..d3435128 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 setuptools==69.5.1
 thrift==0.20.0
 python-keystoneclient==5.4.0
-openstacksdk==3.3.0
+openstacksdk==3.1.0
 deprecated==1.2.14
 Click==8.1.7
 ansible==9.5.1
@@ -17,4 +17,5 @@ types-PyYAML==6.0.12.20240311
 sympy==1.13.0
 colorama==0.4.6
 types-redis==4.6.0.20240425
-gevent
\ No newline at end of file
+gevent
+pytest
diff --git a/simple_vm_client/bibigrid_connector/test_bibigrid_connector.py b/simple_vm_client/bibigrid_connector/test_bibigrid_connector.py
index acb22681..35177498 100644
--- a/simple_vm_client/bibigrid_connector/test_bibigrid_connector.py
+++ b/simple_vm_client/bibigrid_connector/test_bibigrid_connector.py
@@ -6,7 +6,11 @@
 import requests
 
 from simple_vm_client.bibigrid_connector.bibigrid_connector import BibigridConnector
-from simple_vm_client.ttypes import ClusterInfo, ClusterInstance
+from simple_vm_client.ttypes import (
+    ClusterInfo,
+    ClusterInstance,
+    ClusterNotFoundException,
+)
 
 HOST = "example.com"
 PORT = 8080
@@ -200,7 +204,7 @@ def test_start_cluster(self, mock_logger_info, mock_post):
 
         # Call the method to test
         result = self.connector.start_cluster(
-            public_key=public_key,
+            public_keys=[public_key],
             master_instance=DEFAULT_MASTER_INSTANCE,
             worker_instances=DEFAULT_WORKER_INSTANCES,
             user=user,
@@ -271,13 +275,16 @@ def test_get_clusters_info(self, mock_logger_info, mock_get):
         self.assertEqual(result, [{"cluster-id": "fake_cluster_id"}])
         mock_logger_info.assert_called_once_with("Get clusters info")
 
-    @patch.object(BibigridConnector, "get_clusters_info")
+    @patch(
+        "simple_vm_client.bibigrid_connector.bibigrid_connector.BibigridConnector.get_clusters_info"
+    )
     @patch("simple_vm_client.bibigrid_connector.bibigrid_connector.logger.info")
     def test_get_cluster_info_none(self, mock_logger_info, mock_get_clusters_info):
         mock_get_clusters_info.return_value = []
-        result = self.connector.get_cluster_info("fake_cluster_id")
+        with self.assertRaises(ClusterNotFoundException):
+            self.connector.get_cluster_info("fake_cluster_id")
+
         mock_logger_info.assert_any_call("Get Cluster info from fake_cluster_id")
-        self.assertIsNone(result)
 
     @patch.object(BibigridConnector, "get_clusters_info")
     @patch("simple_vm_client.bibigrid_connector.bibigrid_connector.logger.info")
diff --git a/simple_vm_client/openstack_connector/openstack_connector.py b/simple_vm_client/openstack_connector/openstack_connector.py
index 12abb040..6b6895a6 100644
--- a/simple_vm_client/openstack_connector/openstack_connector.py
+++ b/simple_vm_client/openstack_connector/openstack_connector.py
@@ -520,18 +520,27 @@ def get_servers_by_bibigrid_id(self, bibigrid_id: str) -> list[Server]:
         servers: list[Server] = self.openstack_connection.list_servers(filters=filters)
         return servers
 
-    def get_active_image_by_os_version(self, os_version: str, os_distro: str) -> Image:
+    def get_active_image_by_os_version(
+        self, os_version: str, os_distro: Union[str, None]
+    ) -> Image:
         logger.info(f"Get active Image by os-version: {os_version}")
         images = self.openstack_connection.list_images()
         for image in images:
+
             image_os_version = image.get("os_version", None)
             image_os_distro = image.get("os_distro", None)
-            base_image_ref = image.get("properties", {}).get("base_image_ref", None)
+            image_properties = image.get("properties", None)
+            if image_properties:
+
+                base_image_ref = image_properties.get("base_image_ref", None)
+            else:
+                base_image_ref = None
             if (
                 os_version == image_os_version
                 and image.status == "active"
                 and base_image_ref is None
             ):
+
                 if os_distro and os_distro == image_os_distro:
                     return image
                 elif os_distro is None:
diff --git a/simple_vm_client/test_openstack_connector.py b/simple_vm_client/test_openstack_connector.py
index 69a5ea29..8e9dbe51 100644
--- a/simple_vm_client/test_openstack_connector.py
+++ b/simple_vm_client/test_openstack_connector.py
@@ -4,7 +4,7 @@
 import tempfile
 import unittest
 from unittest import mock
-from unittest.mock import MagicMock, call, patch
+from unittest.mock import ANY, MagicMock, call, patch
 
 from openstack.block_storage.v3 import volume
 from openstack.block_storage.v3.limits import Limit
@@ -86,6 +86,8 @@
     id="image_id_2",
     status="active",
     name="image_2",
+    os_version="22.04",
+    os_distro="ubuntu",
     metadata={"os_version": "22.04", "os_distro": "ubuntu"},
     tags=["portalclient"],
 )
@@ -93,6 +95,8 @@
     id="image_inactive",
     status="building",
     name="image_inactive",
+    os_version="22.04",
+    os_distro="ubuntu",
     metadata={"os_version": "22.04", "os_distro": "ubuntu"},
     tags=["portalclient"],
 )
@@ -102,6 +106,8 @@
         id="image_id_1",
         status="inactive",
         name="image_1",
+        os_version="22.04",
+        os_distro="ubuntu",
         metadata={"os_version": "22.04", "os_distro": "ubuntu"},
         tags=["portalclient"],
     ),
@@ -110,6 +116,8 @@
         id="image_id_3",
         status="active",
         name="image_3",
+        os_version="22.04",
+        os_distro="ubuntu",
         metadata={"os_version": "22.04", "os_distro": "centos"},
         tags=["portalclient"],
     ),
@@ -1837,7 +1845,7 @@ def test_start_server(
             image=fake_image.id,
             flavor=fake_flavor.id,
             network=[fake_network.id],
-            key_name=server_keypair.name,
+            key_name=ANY,
             meta=metadata,
             volumes=["volume1", "volume2"],
             userdata="userdata",
@@ -1858,7 +1866,7 @@ def test_start_server(
         )
 
         self.openstack_connector.openstack_connection.create_keypair.assert_called_once_with(
-            name=server_keypair.name, public_key=public_key
+            name=ANY, public_key=public_key
         )
 
         mock_get_volumes.assert_called_once_with(
@@ -1867,9 +1875,9 @@ def test_start_server(
         )
 
         self.openstack_connector.openstack_connection.get_keypair.assert_called_once_with(
-            name_or_id=server_keypair.name
+            name_or_id=ANY
         )
-        mock_delete_keypair.assert_any_call(key_name=server_keypair.name)
+        mock_delete_keypair.assert_any_call(key_name=ANY)
 
         # Check the result
         self.assertEqual(result, server.id)
diff --git a/simple_vm_client/test_virtualmachinehandler.py b/simple_vm_client/test_virtualmachinehandler.py
index 060b23e4..dc10ddf3 100644
--- a/simple_vm_client/test_virtualmachinehandler.py
+++ b/simple_vm_client/test_virtualmachinehandler.py
@@ -452,6 +452,7 @@ def test_start_server_with_res(self):
             additional_keys=[],
             research_environment_metadata="res_metadata",
             additional_security_group_ids=[],
+            slurm_version=None,
         )
 
     def test_start_server(self):
@@ -478,6 +479,7 @@ def test_start_server(self):
             additional_keys=[],
             research_environment_metadata=None,
             additional_security_group_ids=[],
+            slurm_version=None,
         )
 
     def test_start_server_with_custom_key(self):
@@ -598,13 +600,13 @@ def test_start_cluster(self):
         master = MagicMock()
         worker_instances = [MagicMock()]
         self.handler.start_cluster(
-            public_key="pub",
+            public_keys=["pub"],
             master_instance=master,
             worker_instances=worker_instances,
             user=USERNAME,
         )
         self.handler.bibigrid_connector.start_cluster.assert_called_once_with(
-            public_key="pub",
+            public_keys=["pub"],
             master_instance=master,
             worker_instances=worker_instances,
             user=USERNAME,