diff --git a/nav2_bringup/nav2_gazebo_spawner/nav2_gazebo_spawner/nav2_gazebo_spawner.py b/nav2_bringup/nav2_gazebo_spawner/nav2_gazebo_spawner/nav2_gazebo_spawner.py
index 00f7012779..8ca57f41de 100644
--- a/nav2_bringup/nav2_gazebo_spawner/nav2_gazebo_spawner/nav2_gazebo_spawner.py
+++ b/nav2_bringup/nav2_gazebo_spawner/nav2_gazebo_spawner/nav2_gazebo_spawner.py
@@ -87,7 +87,7 @@ def main():
     if args.robot_namespace:
         ros_params = plugin.find('ros')
         ros_tf_remap = ET.SubElement(ros_params, 'remapping')
-        ros_tf_remap.text = f"/tf:=/{args.robot_namespace}/tf"
+        ros_tf_remap.text = f'/tf:=/{args.robot_namespace}/tf'
 
     # Set data for request
     request = SpawnEntity.Request()
diff --git a/nav2_simple_commander/nav2_simple_commander/demo_picking.py b/nav2_simple_commander/nav2_simple_commander/demo_picking.py
index a93e1e60ae..8cfcb2aec3 100644
--- a/nav2_simple_commander/nav2_simple_commander/demo_picking.py
+++ b/nav2_simple_commander/nav2_simple_commander/demo_picking.py
@@ -75,7 +75,7 @@ def main():
     shelf_item_pose.pose.position.y = shelf_positions[request_item_location][1]
     shelf_item_pose.pose.orientation.z = 1.0
     shelf_item_pose.pose.orientation.w = 0.0
-    print(f"Received request for item picking at {request_item_location}.")
+    print(f'Received request for item picking at {request_item_location}.')
     navigator.goToPose(shelf_item_pose)
 
     # Do something during our route
@@ -105,12 +105,12 @@ def main():
         navigator.goToPose(shipping_destination)
 
     elif result == NavigationResult.CANCELED:
-        print(f"Task at {request_item_location} was canceled. Returning to staging point...")
+        print(f'Task at {request_item_location} was canceled. Returning to staging point...')
         initial_pose.header.stamp = navigator.get_clock().now().to_msg()
         navigator.goToPose(initial_pose)
 
     elif result == NavigationResult.FAILED:
-        print(f"Task at {request_item_location} failed!")
+        print(f'Task at {request_item_location} failed!')
         exit(-1)
 
     while not navigator.isNavComplete():
diff --git a/nav2_simple_commander/nav2_simple_commander/robot_navigator.py b/nav2_simple_commander/nav2_simple_commander/robot_navigator.py
index e16b5df3b3..80c21cfb58 100644
--- a/nav2_simple_commander/nav2_simple_commander/robot_navigator.py
+++ b/nav2_simple_commander/nav2_simple_commander/robot_navigator.py
@@ -96,14 +96,14 @@ def goThroughPoses(self, poses):
         goal_msg = NavigateThroughPoses.Goal()
         goal_msg.poses = poses
 
-        self.info(f"Navigating with {len(goal_msg.poses)} goals....")
+        self.info(f'Navigating with {len(goal_msg.poses)} goals....')
         send_goal_future = self.nav_through_poses_client.send_goal_async(goal_msg,
                                                                          self._feedbackCallback)
         rclpy.spin_until_future_complete(self, send_goal_future)
         self.goal_handle = send_goal_future.result()
 
         if not self.goal_handle.accepted:
-            self.error(f"Goal with {len(poses)} poses was rejected!")
+            self.error(f'Goal with {len(poses)} poses was rejected!')
             return False
 
         self.result_future = self.goal_handle.get_result_async()
@@ -142,14 +142,14 @@ def followWaypoints(self, poses):
         goal_msg = FollowWaypoints.Goal()
         goal_msg.poses = poses
 
-        self.info(f"Following {len(goal_msg.poses)} goals....")
+        self.info(f'Following {len(goal_msg.poses)} goals....')
         send_goal_future = self.follow_waypoints_client.send_goal_async(goal_msg,
                                                                         self._feedbackCallback)
         rclpy.spin_until_future_complete(self, send_goal_future)
         self.goal_handle = send_goal_future.result()
 
         if not self.goal_handle.accepted:
-            self.error(f"Following {len(poses)} waypoints request was rejected!")
+            self.error(f'Following {len(poses)} waypoints request was rejected!')
             return False
 
         self.result_future = self.goal_handle.get_result_async()
@@ -322,10 +322,10 @@ def lifecycleStartup(self):
         self.info('Starting up lifecycle nodes based on lifecycle_manager.')
         for srv_name, srv_type in self.get_service_names_and_types():
             if srv_type[0] == 'nav2_msgs/srv/ManageLifecycleNodes':
-                self.info(f"Starting up {srv_name}")
+                self.info(f'Starting up {srv_name}')
                 mgr_client = self.create_client(ManageLifecycleNodes, srv_name)
                 while not mgr_client.wait_for_service(timeout_sec=1.0):
-                    self.info(f"{srv_name} service not available, waiting...")
+                    self.info(f'{srv_name} service not available, waiting...')
                 req = ManageLifecycleNodes.Request()
                 req.command = ManageLifecycleNodes.Request().STARTUP
                 future = mgr_client.call_async(req)
@@ -346,10 +346,10 @@ def lifecycleShutdown(self):
         self.info('Shutting down lifecycle nodes based on lifecycle_manager.')
         for srv_name, srv_type in self.get_service_names_and_types():
             if srv_type[0] == 'nav2_msgs/srv/ManageLifecycleNodes':
-                self.info(f"Shutting down {srv_name}")
+                self.info(f'Shutting down {srv_name}')
                 mgr_client = self.create_client(ManageLifecycleNodes, srv_name)
                 while not mgr_client.wait_for_service(timeout_sec=1.0):
-                    self.info(f"{srv_name} service not available, waiting...")
+                    self.info(f'{srv_name} service not available, waiting...')
                 req = ManageLifecycleNodes.Request()
                 req.command = ManageLifecycleNodes.Request().SHUTDOWN
                 future = mgr_client.call_async(req)
@@ -359,16 +359,16 @@ def lifecycleShutdown(self):
 
     def _waitForNodeToActivate(self, node_name):
         # Waits for the node within the tester namespace to become active
-        self.debug(f"Waiting for {node_name} to become active..")
-        node_service = f"{node_name}/get_state"
+        self.debug(f'Waiting for {node_name} to become active..')
+        node_service = f'{node_name}/get_state'
         state_client = self.create_client(GetState, node_service)
         while not state_client.wait_for_service(timeout_sec=1.0):
-            self.info(f"{node_service} service not available, waiting...")
+            self.info(f'{node_service} service not available, waiting...')
 
         req = GetState.Request()
         state = 'unknown'
         while state != 'active':
-            self.debug(f"Getting {node_name} state...")
+            self.debug(f'Getting {node_name} state...')
             future = state_client.call_async(req)
             rclpy.spin_until_future_complete(self, future)
             if future.result() is not None:
diff --git a/nav2_system_tests/src/costmap_filters/tester_node.py b/nav2_system_tests/src/costmap_filters/tester_node.py
index 41f0511bae..0a61116254 100755
--- a/nav2_system_tests/src/costmap_filters/tester_node.py
+++ b/nav2_system_tests/src/costmap_filters/tester_node.py
@@ -230,7 +230,7 @@ def checkKeepout(self, x, y):
             self.warn_msg('Filter mask was not received')
         elif self.isInKeepout(x, y):
             self.filter_test_result = False
-            self.error_msg(f"Pose ({x}, {y}) belongs to keepout zone")
+            self.error_msg(f'Pose ({x}, {y}) belongs to keepout zone')
             return False
         return True
 
@@ -285,7 +285,7 @@ def dwbCostCloudCallback(self, msg):
             self.cost_cloud_received = True
 
     def speedLimitCallback(self, msg):
-        self.info_msg(f"Received speed limit: {msg.speed_limit}")
+        self.info_msg(f'Received speed limit: {msg.speed_limit}')
         self.checkSpeed(self.speed_it, msg.speed_limit)
         self.speed_it += 1
 
@@ -339,20 +339,20 @@ def distanceFromGoal(self):
         d_x = self.current_pose.position.x - self.goal_pose.position.x
         d_y = self.current_pose.position.y - self.goal_pose.position.y
         distance = math.sqrt(d_x * d_x + d_y * d_y)
-        self.info_msg(f"Distance from goal is: {distance}")
+        self.info_msg(f'Distance from goal is: {distance}')
         return distance
 
     def wait_for_node_active(self, node_name: str):
         # Waits for the node within the tester namespace to become active
-        self.info_msg(f"Waiting for {node_name} to become active")
-        node_service = f"{node_name}/get_state"
+        self.info_msg(f'Waiting for {node_name} to become active')
+        node_service = f'{node_name}/get_state'
         state_client = self.create_client(GetState, node_service)
         while not state_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{node_service} service not available, waiting...")
+            self.info_msg(f'{node_service} service not available, waiting...')
         req = GetState.Request()  # empty request
         state = 'UNKNOWN'
         while (state != 'active'):
-            self.info_msg(f"Getting {node_name} state...")
+            self.info_msg(f'Getting {node_name} state...')
             future = state_client.call_async(req)
             rclpy.spin_until_future_complete(self, future)
             if future.result() is not None:
@@ -371,7 +371,7 @@ def shutdown(self):
         mgr_client = self.create_client(
             ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
@@ -388,7 +388,7 @@ def shutdown(self):
         mgr_client = self.create_client(
             ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
diff --git a/nav2_system_tests/src/system/nav_through_poses_tester_node.py b/nav2_system_tests/src/system/nav_through_poses_tester_node.py
index 7cd95c7f7b..ac7356cfa4 100755
--- a/nav2_system_tests/src/system/nav_through_poses_tester_node.py
+++ b/nav2_system_tests/src/system/nav_through_poses_tester_node.py
@@ -124,15 +124,15 @@ def poseCallback(self, msg):
 
     def wait_for_node_active(self, node_name: str):
         # Waits for the node within the tester namespace to become active
-        self.info_msg(f"Waiting for {node_name} to become active")
-        node_service = f"{node_name}/get_state"
+        self.info_msg(f'Waiting for {node_name} to become active')
+        node_service = f'{node_name}/get_state'
         state_client = self.create_client(GetState, node_service)
         while not state_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{node_service} service not available, waiting...")
+            self.info_msg(f'{node_service} service not available, waiting...')
         req = GetState.Request()  # empty request
         state = 'UNKNOWN'
         while (state != 'active'):
-            self.info_msg(f"Getting {node_name} state...")
+            self.info_msg(f'Getting {node_name} state...')
             future = state_client.call_async(req)
             rclpy.spin_until_future_complete(self, future)
             if future.result() is not None:
@@ -149,7 +149,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_navigation/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
@@ -164,7 +164,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_localization/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
diff --git a/nav2_system_tests/src/system/nav_to_pose_tester_node.py b/nav2_system_tests/src/system/nav_to_pose_tester_node.py
index aff1793176..fb038a1a59 100755
--- a/nav2_system_tests/src/system/nav_to_pose_tester_node.py
+++ b/nav2_system_tests/src/system/nav_to_pose_tester_node.py
@@ -133,7 +133,7 @@ def runNavigateAction(self, goal_pose: Optional[Pose] = None):
                     self.error_msg('Failed GROOT_BT - Get Status from ZMQ Publisher')
                     future_return = False
             except Exception as e:  # noqa: B902
-                self.error_msg(f"Failed GROOT_BT - ZMQ Tests: {e.__doc__}{e.message}")
+                self.error_msg(f'Failed GROOT_BT - ZMQ Tests: {e.__doc__}{e.message}')
                 future_return = False
 
         self.info_msg("Waiting for 'NavigateToPose' action to complete")
@@ -159,8 +159,8 @@ def grootMonitoringReloadTree(self):
         sock.setsockopt(zmq.RCVTIMEO, 1000)
         # sock.setsockopt(zmq.LINGER, 0)
 
-        sock.connect(f"tcp://localhost: {port}")
-        self.info_msg(f"ZMQ Server Port: {port}")
+        sock.connect(f'tcp://localhost: {port}')
+        self.info_msg(f'ZMQ Server Port: {port}')
 
         # this should fail
         try:
@@ -206,7 +206,7 @@ def grootMonitoringGetStatus(self):
         # Define subscription and messages with prefix to accept.
         sock.setsockopt_string(zmq.SUBSCRIBE, '')
         port = 1666  # default publishing port for groot monitoring
-        sock.connect(f"tcp://127.0.0.1:{port}")
+        sock.connect(f'tcp://127.0.0.1:{port}')
 
         for request in range(3):
             try:
@@ -242,20 +242,20 @@ def distanceFromGoal(self):
         d_x = self.current_pose.position.x - self.goal_pose.position.x
         d_y = self.current_pose.position.y - self.goal_pose.position.y
         distance = math.sqrt(d_x * d_x + d_y * d_y)
-        self.info_msg(f"Distance from goal is: {distance}")
+        self.info_msg(f'Distance from goal is: {distance}')
         return distance
 
     def wait_for_node_active(self, node_name: str):
         # Waits for the node within the tester namespace to become active
-        self.info_msg(f"Waiting for {node_name} to become active")
-        node_service = f"{node_name}/get_state"
+        self.info_msg(f'Waiting for {node_name} to become active')
+        node_service = f'{node_name}/get_state'
         state_client = self.create_client(GetState, node_service)
         while not state_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{node_service} service not available, waiting...")
+            self.info_msg(f'{node_service} service not available, waiting...')
         req = GetState.Request()  # empty request
         state = 'UNKNOWN'
         while (state != 'active'):
-            self.info_msg(f"Getting {node_name} state...")
+            self.info_msg(f'Getting {node_name} state...')
             future = state_client.call_async(req)
             rclpy.spin_until_future_complete(self, future)
             if future.result() is not None:
@@ -272,7 +272,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_navigation/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
@@ -287,7 +287,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_localization/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
diff --git a/nav2_system_tests/src/system_failure/tester_node.py b/nav2_system_tests/src/system_failure/tester_node.py
index 168f161155..e4b3a9baeb 100755
--- a/nav2_system_tests/src/system_failure/tester_node.py
+++ b/nav2_system_tests/src/system_failure/tester_node.py
@@ -146,20 +146,20 @@ def distanceFromGoal(self):
         d_x = self.current_pose.position.x - self.goal_pose.position.x
         d_y = self.current_pose.position.y - self.goal_pose.position.y
         distance = math.sqrt(d_x * d_x + d_y * d_y)
-        self.info_msg(f"Distance from goal is: {distance}")
+        self.info_msg(f'Distance from goal is: {distance}')
         return distance
 
     def wait_for_node_active(self, node_name: str):
         # Waits for the node within the tester namespace to become active
-        self.info_msg(f"Waiting for {node_name} to become active")
-        node_service = f"{node_name}/get_state"
+        self.info_msg(f'Waiting for {node_name} to become active')
+        node_service = f'{node_name}/get_state'
         state_client = self.create_client(GetState, node_service)
         while not state_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{node_service} service not available, waiting...")
+            self.info_msg(f'{node_service} service not available, waiting...')
         req = GetState.Request()  # empty request
         state = 'UNKNOWN'
         while (state != 'active'):
-            self.info_msg(f"Getting {node_name} state...")
+            self.info_msg(f'Getting {node_name} state...')
             future = state_client.call_async(req)
             rclpy.spin_until_future_complete(self, future)
             if future.result() is not None:
@@ -176,7 +176,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_navigation/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
@@ -191,7 +191,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_localization/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
diff --git a/nav2_system_tests/src/waypoint_follower/tester.py b/nav2_system_tests/src/waypoint_follower/tester.py
index 5b2555b60e..e6d299caa5 100755
--- a/nav2_system_tests/src/waypoint_follower/tester.py
+++ b/nav2_system_tests/src/waypoint_follower/tester.py
@@ -130,7 +130,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_navigation/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
@@ -146,7 +146,7 @@ def shutdown(self):
         transition_service = 'lifecycle_manager_localization/manage_nodes'
         mgr_client = self.create_client(ManageLifecycleNodes, transition_service)
         while not mgr_client.wait_for_service(timeout_sec=1.0):
-            self.info_msg(f"{transition_service} service not available, waiting...")
+            self.info_msg(f'{transition_service} service not available, waiting...')
 
         req = ManageLifecycleNodes.Request()
         req.command = ManageLifecycleNodes.Request().SHUTDOWN
diff --git a/tools/bt2img.py b/tools/bt2img.py
index a1c76029a6..31480f19be 100755
--- a/tools/bt2img.py
+++ b/tools/bt2img.py
@@ -89,7 +89,7 @@ def main():
         legend.render(args.legend)
     dot.format = 'png'
     if args.save_dot:
-        print(f"Saving dot to {args.save_dot}")
+        print(f'Saving dot to {args.save_dot}')
         args.save_dot.write(dot.source)
     dot.render(args.image_out, view=args.display)
 
@@ -119,7 +119,7 @@ def find_behavior_tree(xml_tree, tree_name):
         if tree_name == tree.get('ID'):
             return tree
 
-    raise RuntimeError(f"No behavior tree for name {tree_name} found in the XML file")
+    raise RuntimeError(f'No behavior tree for name {tree_name} found in the XML file')
 
 # Generate a dot description of the root of the behavior tree.
 def convert2dot(behavior_tree):
@@ -157,13 +157,13 @@ def add_nodes(dot, parent_dot_name, parent_node):
 # type, the name if provided, and the parameters.
 def make_label(node):
     label = '< <table border="0" cellspacing="0" cellpadding="0">'
-    label += f"<tr><td align=\"text\"><i>{node.tag}</i></td></tr>"
+    label += '<tr><td align="text"><i>' + node.tag + '</i></td></tr>'
     name = node.get('name')
     if name:
-        label += f"<tr><td align=\"text\"><b>{name}</b></td></tr>"
+        label += '<tr><td align="text"><b>' + name + '</b></td></tr>'
 
     for (param_name, value) in node.items():
-        label += f"<tr><td align=\"left\"><sub>{param_name}={value}</sub></td></tr>"
+        label += '<tr><td align="left"><sub>' + param_name + '=' + value + '</sub></td></tr>'
     label += '</table> >'
     return label