Pricing
00
In productionProbeginnerParameters

Reading a parameter crashes the node

Let the node read `publish_rate` without crashing, keeping the same default.

Pairs with Parameters and configuration in Learn ROS 2 from the basics. Read the concept first, then diagnose it here.

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Operator report

The node throws ParameterNotDeclaredException on startup.

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

01

System boundary

Trace only the relevant path.

3 nodes
  1. 01declare_parameter→
  2. 02get_parameter→
  3. 03timer periodOUT
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
  • Parameter is declared
  • The node starts
  • Hidden regression behavior
  • Root cause explanation