# Simulation Broken? - C++ Basics for Robotics

**URL:** <https://get-help.theconstruct.ai/t/simulation-broken-c-basics-for-robotics/40829>\
**Category:** General Support\
**Created:** [April 27, 2026, 9:09pm UTC](https://get-help.theconstruct.ai/t/simulation-broken-c-basics-for-robotics/40829 "2026-04-27T21:09:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![lichtphyz](https://get-help.theconstruct.ai/letter_avatar_proxy/v4/letter/l/ecae2f/32.png) [@lichtphyz](https://get-help.theconstruct.ai/u/lichtphyz)\
**Post date:** [April 27, 2026, 9:09pm UTC](https://get-help.theconstruct.ai/t/simulation-broken-c-basics-for-robotics/40829/1 "2026-04-27T21:09:22Z")

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I’m trying to complete the project for the C++ Basics for Robotics course, got mid-way through coding up the final project, but now the simulation will not start any more.  
running:  
ros2 launch turtlebot3\_gazebo main\_turtlebot3\_lab.launch.xml  
does bring up the guacamole window, but the simulation no longer appears (often the simulation window does appear, but not simulation appears within it.

The terminal has error messages such as:

[ERROR] [spawn\_entity.py-4]: process has died [pid 8521, exit code 1, cmd ‘/opt/ros/humble/lib/gazebo\_ros/spawn\_entity.py -entity burger -file /home/user/simulation\_ws/install/turtlebot3\_gazebo/share/turtlebot3\_gazebo/models/turtlebot3\_burger/model.sdf -x 0.0 -y 0.5 -z 0.01 --ros-args’].

The first couple of times I was able to restart the simulation, but not any more. It just hangs and never appears. This has been a giant pain. I’ve spend far more time troubleshooting the simulation than coding. I was hoping to take a number of your courses, but if this is the state of the simulation in the primary introductory class I’m very concerned that more will be a similar waste of time. Hoping there’s an easy solution I’m missing.

Is there some kind of full reset I can do? Exiting and re-entering the course does not fix the problem.

 ![Screenshot 2026-04-27 141007](https://get-help.theconstruct.ai/uploads/default/original/2X/4/4e53197c4530262ba0e6e6fa09f45f069742de23.jpeg)

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**Author:** ![bayodesegun](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/bayodesegun/32/10684_2.png) [@bayodesegun](https://get-help.theconstruct.ai/u/bayodesegun)\
**Post date:** [April 28, 2026, 11:08am UTC](https://get-help.theconstruct.ai/t/simulation-broken-c-basics-for-robotics/40829/2 "2026-04-28T11:08:58Z")

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I apologize for that glitch @lichtphyz. That was an unfortunately error that sometimes happen with Gazebo, but which usually goes away on a second try.

Please try again.

To fully reset a simulation, you need to exit it and open something else (like a course) and then exit that something else and come back to the project.

We are working on using more stable simulations across our courses and projects, so you can’t be sure you won’t always experience this in other courses. Thank you for your understanding.

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**Author:** ![system](https://get-help.theconstruct.ai/uploads/default/original/2X/9/9d3ce8305cc0d0d9b6e07d15767a6f245c526f1b.jpeg) [@system](https://get-help.theconstruct.ai/u/system)\
**Post date:** [May 8, 2026, 11:09am UTC](https://get-help.theconstruct.ai/t/simulation-broken-c-basics-for-robotics/40829/3 "2026-05-08T11:09:07Z")

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