No transition matching 3 found for current state

edit

I'm looking at the ros2 lifecycles demo here: https://github.com/ros2/demos/blob/fo...

According to the Lifecycles page of ROS2 if an exception occurs in any of the primary states then the on_error method should be called, which in turn, on SUCCESS reverts to the Unconfigured state, and on FAILUREit goes to Finalized and eventually the node gets shutdown.

For the sake of the example I'll throw an exception from within one of the transition callbacks, e.g., on_activate.

on_activate(const rclcpp_lifecycle::State &)
{
  throw std::runtime_error("some_error");
  ...

With this change in place I see the following transitions happening (see roslaunch output of command ros2 launch lifecycle lifecycle_demo.launch.py)

[lifecycle_listener-2] [INFO] [1627469418.643524277] [lc_listener]: notify callback: Transition from state activating to errorprocessing
[lifecycle_listener-2] [INFO] [1627469418.643625385] [lc_listener]: notify callback: Transition from state errorprocessing to unconfigured
[lifecycle_service_client-3] [WARN] [1627469418.643600791] [lc_client]: Failed to trigger transition 3

I understand why it transitions to errorprocessing and then to unconfigured. However it then tries to transition to "3" which is the TRANSITION_ACTIVATE transition and it fails to do so since that is not a valid transition (Unconfigured -> Active)

I don't understand though, why is it trying transition to activate since I or any other node didn't explicitly trigger this transition? What can I do to solve this?

Here's also the full list of transitions the node goes through, in case it's helpful

ros2 topic echo /lc_talker/transition_event
timestamp: 0
transition:
  id: 0
  label: ''
start_state:
  id: 1
  label: unconfigured
goal_state:
  id: 10
  label: configuring
---
timestamp: 0
transition:
  id: 0
  label: ''
start_state:
  id: 10
  label: configuring
goal_state:
  id: 2
  label: inactive
---
timestamp: 0
transition:
  id: 0
  label: ''
start_state:
  id: 2
  label: inactive
goal_state:
  id: 13
  label: activating
---
timestamp: 0
transition:
  id: 0
  label: ''
start_state:
  id: 13
  label: activating
goal_state:
  id: 15
  label: errorprocessing
---
timestamp: 0
transition:
  id: 0
  label: ''
start_state:
  id: 15
  label: errorprocessing
goal_state:
  id: 1
  label: unconfigured
---

System Information

I'm using:

• Ubuntu 20.04
• Latest version of the PPA packages of ROS Foxy.

Any pointers?