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00
In productionProbeginnerTopic wiring

The subscriber hears nothing

Make the listener receive the talker's messages without changing the talker.

Pairs with Topics, publishers, and subscribers in Learn ROS 2 from the basics. Read the concept first, then diagnose it here.

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Operator report

`ros2 topic echo` on the listener's topic is silent even though the talker is publishing.

Ubuntu 24.04, ROS 2 Jazzy, rclpy, a single-package browser workspace

01

System boundary

Trace only the relevant path.

3 nodes
  1. 01publisher topic→
  2. 02topic name match→
  3. 03subscriber topicOUT
02

How this lab works

You diagnose it. No command list.

Open the repair workspace and gather your own evidence in a real terminal. No diagnostic commands are handed to you - finding the fault is the exercise. Stuck? Progressive hints unlock inside the workspace.

03

Verification

Pass more than the visible symptom.

4 checks
  • Topic names match
  • Messages are received
  • Hidden regression behavior
  • Root cause explanation