# RMW_IMPLEMENTATION=rmw_fastrtps_cpp: Failed to find RMW implementation: 'rmw_fastrtps_cpp' not found in package list

- **ID:** `ros2/rmw-implementation-not-found`
- **Domain:** ros2
- **Category:** install_error
- **Verification:** ai_generated
- **Fix Rate:** 95%

## Root Cause

The specified RMW implementation package is not installed in the ROS2 environment, often due to incomplete installation or incorrect workspace sourcing.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| Humble | active | — | — |
| Iron | active | — | — |
| Jazzy | active | — | — |
| Rolling | active | — | — |

## Workarounds

1. **Install the missing RMW implementation package using apt.** (95% success)
   ```
   Install the missing RMW implementation package using apt.
   ```
2. **List available RMW implementations and choose an installed one.** (90% success)
   ```
   List available RMW implementations and choose an installed one.
   ```
3. **Ensure the ROS2 setup script is sourced before checking RMW availability.** (85% success)
   ```
   Ensure the ROS2 setup script is sourced before checking RMW availability.
   ```

## Dead Ends

- **Setting RMW_IMPLEMENTATION to a random string like 'rmw_cyclonedds_cpp' without installing it** — Only installed RMW implementations are available; setting an uninstalled one causes the same error. (90% fail)
- **Rebuilding all packages with colcon build** — The RMW implementation is a system package, not a workspace package; rebuilding doesn't install it. (50% fail)
- **Setting RMW_IMPLEMENTATION in .bashrc without sourcing the ROS2 setup file** — The environment variable is set but the ROS2 installation isn't sourced, so packages aren't found. (60% fail)