Common Errors

Slicer_DIR Not Found

If CMake cannot find Slicer, the build may fail with:

Could not find a package configuration file provided by "Slicer"

Set Slicer_DIR to the Slicer build directory:

colcon build --cmake-args \
  -DSlicer_DIR:PATH=/path/to/Slicer-SuperBuild/Slicer-build \
  -DCMAKE_BUILD_TYPE=Release

After the first successful configure, future builds usually only need:

colcon build

Missing ROS Packages

If CMake reports a missing ROS package, source ROS and install the package for the active ROS distribution:

source /opt/ros/jazzy/setup.bash
sudo apt install ros-$ROS_DISTRO-<package-name>

The main package dependencies are listed in package.xml. Additional system packages are listed in Compatibility.

Wrong Python Environment

Slicer and ROS 2 use different Python environments. Build from a terminal where ROS 2 has been sourced, and let the SlicerROS2 CMake configuration switch between the ROS Python and Slicer Python as needed.

If CMake cache entries point to the wrong Python executable, reconfigure the package build directory with ccmake or cmake-gui:

ccmake ~/ros2_ws/build/slicer_ros2_module

SlicerROS2 Module Does Not Appear

Make sure the workspace setup file has been sourced and Slicer was started with the wrapper:

source ~/ros2_ws/install/setup.bash
ros2 run slicer_ros2_module slicer

Starting the Slicer executable directly can skip the module paths configured by the ROS 2 workspace. See Launching Slicer for the recommended launcher and examples.

MoveIt Controls Are Disabled

The motion-control module expects a robot loaded in SlicerROS2 and an available MoveIt configuration. Confirm that the robot description, SRDF, planning group, and MoveIt services/actions are available before planning trajectories. See Robot Visualization for robot loading and Motion Control for MoveIt setup.

No Joint States Received

If joint sliders remain at zero or current-state commands report missing joint states, confirm that a sensor_msgs/msg/JointState publisher is active and that the topic name matches the configured joint-state topic.