# \[Bug\] Intermediate ROS2: simulation stuck on loading

**URL:** <https://get-help.theconstruct.ai/t/bug-intermediate-ros2-simulation-stuck-on-loading/42961>\
**Category:** Intermediate ROS2\
**Created:** [October 27, 2026, 12:10pm UTC](https://get-help.theconstruct.ai/t/bug-intermediate-ros2-simulation-stuck-on-loading/42961 "2026-10-27T12:10:19Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dasariarjun1623](https://get-help.theconstruct.ai/letter_avatar_proxy/v4/letter/d/dfb087/32.png) [@dasariarjun1623](https://get-help.theconstruct.ai/u/dasariarjun1623)\
**Post date:** [October 27, 2026, 12:10pm UTC](https://get-help.theconstruct.ai/t/bug-intermediate-ros2-simulation-stuck-on-loading/42961/1 "2026-10-27T12:10:19Z")

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This is an error report.

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**Screenshot of the error**

 ![](https://error-imgs.s3.amazonaws.com/error_image_66353470-843f-4a3c-8884-7d1242d85fa9_1793102934331.png)
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**Error details**

The simulation window in Intermediate ROS2 never finishes loading. It stays on "Loading Simulation..." indefinitely (screenshot attached). The notebook, code editor and terminals all work.

What I already tried:

- Waited 20+ minutes
- Reloaded the simulation panel
- Exited and reopened the course
- Switched to a different network
- Disabled uBlock Origin for app.theconstruct.ai and reloaded
- Checked ~/.bashrc: unmodified (default file, nothing added after The Construct's note)

The simulation in "ROS2 Basics in 5 Days (Python)" loads fine with the same browser and network (Firefox), so it seems specific to this course's environment.

Same symptom as the closed Nov 2024 thread "[Bug] Simulation Not Working" in the Intermediate ROS2 category.

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<div class="post-metadata">

**Author:** ![rtellez](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/rtellez/32/9813_2.png) [@rtellez](https://get-help.theconstruct.ai/u/rtellez)\
**Post date:** [October 27, 2026, 3:45pm UTC](https://get-help.theconstruct.ai/t/bug-intermediate-ros2-simulation-stuck-on-loading/42961/3 "2026-10-27T15:45:01Z")

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Hi Arjun,

we are in the process of getting rid of those Gazebo simulations that crash all the time. We have a new version of the course with a brand new simulation system developed by us.

While we are finishing the final version, you have two options here:

1. Open the course that crashes and then press the “relaunch simulation” icon in the top right corner of the simulation window. This will re-start the sim and launch it properly on the second time for sure

2. Open instead the C++ version of the course ([The Construct - Where Your Robotics Career Happens](https://app.theconstruct.ai/courses/intermediate-ros-2-c-423)). It is quite similar to the Python version. This version has already the new simulation system and works as charm

I apologize for the inconvenience this may have caused you