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Troubleshooting

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Raul Ghișa edited this page Oct 8, 2026 · 2 revisions

FAQs

Q1. Gazebo opens with an empty world and the robot doesn't appear. What should I do?

Wait until Gazebo has fully loaded the empty world (without the robot). Then press Ctrl + C in the terminal to stop it and run the launch command again.

Q2. I am getting a segmentation fault or an error I don't recognise. Who should I ask?

First, ask a TA to look at it. If the TA can't resolve it either, scan the QR code and report it to the technical team.

Q3. I'm seeing simple errors like "package not found" or packages not being detected. How do I fix this?

Rebuild the dev container:

  1. Press Ctrl + Shift + P and select Reopen Folder Locally.
  2. Press Ctrl + Shift + P again and select Rebuild Without Cache.

You can also use this fix whenever a new error appears that seems environment-related.

Q4. rqt keeps crashing when I open the current topic. What should I do?

Close the image visualiser that is already open, then start a fresh one from the Plugins -> Visualization -> Image View menu.

Q5. I can't see the "Reopen in Container" button in VS Code. What's wrong?

Make sure you have opened the correct directory in VS Code: COMP4034 -> src. The button only appears when VS Code is opened in the right folder.

Q6. The package I just built won't run. What should I check?

  1. Make sure the package is placed inside ros2_ws/src.
  2. Go back to the workspace root with cd .. so you are in ros2_ws.
  3. Run colcon build from there.

Q7. Objects appearing in Gazebo (where they shouldn't)

If you reset Gazebo, you may find objects appearing where they shouldn't. This is caused by a cache error in Gazebo. Close Gazebo (ctrl+c In the terminal where Gazebo is running) then run:

  1. pkill -9 gzserver gzclient
  2. rm -rf /tmp/gazebo*

Quick escalation guide: See if the FAQs cover the issue, then ask a TA present, then scan the QR code to report it to the technical team.

Welcome! We are delighted for you to use and adapt the materials from this introductory Autonomous Mobile Robotics module.

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0): You are free to share and adapt it for teaching, research and personal projects, as long as you give appropriate credit and do not use it commercially (for example, by selling it or using it as the basis for a paid service).

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