# \[Bug\] /laser\_scan topic shows no data

**URL:** <https://get-help.theconstruct.ai/t/bug-laser-scan-topic-shows-no-data/40687>\
**Category:** ROS2 Basics in 5 Days Humble (C++)\
**Tags:** ros2\
**Created:** [April 14, 2026, 1:07pm UTC](https://get-help.theconstruct.ai/t/bug-laser-scan-topic-shows-no-data/40687 "2026-04-14T13:07:24Z")\
**Posts on this page:** 1\
**Showing post:** 2

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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 17, 2026, 11:49am UTC](https://get-help.theconstruct.ai/t/bug-laser-scan-topic-shows-no-data/40687/2 "2026-04-17T11:49:13Z")

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I’m sorry you ran into this issue.

You have a red dot in the top-left corner of the simulation window, so the simulation is not working properly and you couldn’t see the topic data.

Please take a look at the following troubleshooting guide for resolving the red dots problem

- [How to fix an unresponsive simulation with red square dots in top-left corner](https://get-help.theconstruct.ai/t/how-to-fix-an-unresponsive-simulation-with-red-square-dots-in-top-left-corner/38962)

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_[View the full topic](https://get-help.theconstruct.ai/t/bug-laser-scan-topic-shows-no-data/40687)._