ros2 type_error ai_generated true

RMW_IMPLEMENTATION=rmw_fastrtps_cpp: Type 'my_msgs/msg/MyType' is not supported by this RMW implementation

ID: ros2/rmw-impl-unsupported-type

Also available as: JSON · Markdown · 中文
80%Fix Rate
85%Confidence
1Evidence
2023-08-15First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
ROS2 Humble active — — —
ROS2 Iron active — — —
ROS2 Rolling active — — —

Root Cause

The custom message type uses a field type (e.g., nested arrays, unbounded sequences with complex types) that the selected RMW implementation (e.g., rmw_fastrtps_cpp) cannot serialize due to DDS type system limitations.

generic

中文

自定义消息类型使用了所选RMW实现（如rmw_fastrtps_cpp）无法序列化的字段类型（如嵌套数组、带复杂类型的无界序列），这是DDS类型系统的限制。

Official Documentation

https://docs.ros.org/en/humble/Concepts/About-RMW-Implementations.html

Workarounds

  1. 85% success Simplify the message type: replace nested sequences with flattened fields or use bounded sequences. For example, change 'float64[] data' to 'float64[100] data' if max size is known. 
    Simplify the message type: replace nested sequences with flattened fields or use bounded sequences. For example, change 'float64[] data' to 'float64[100] data' if max size is known.
  2. 75% success Switch to a different RMW implementation that supports the type better, e.g., set RMW_IMPLEMENTATION=rmw_connextdds (if licensed) and test with the same message. 
    Switch to a different RMW implementation that supports the type better, e.g., set RMW_IMPLEMENTATION=rmw_connextdds (if licensed) and test with the same message.
  3. 80% success Split the complex message into multiple simpler messages and publish them on separate topics, then synchronize in the subscriber node. 
    Split the complex message into multiple simpler messages and publish them on separate topics, then synchronize in the subscriber node.

中文步骤

  1. 简化消息类型：将嵌套序列替换为扁平字段或使用有界序列。例如，如果最大大小已知，将'float64[] data'改为'float64[100] data'。
  2. 切换到其他RMW实现以更好地支持该类型，例如设置RMW_IMPLEMENTATION=rmw_connextdds（如果已授权）并使用相同消息测试。
  3. 将复杂消息拆分为多个简单消息，发布到不同话题，然后在订阅者节点中同步。

Dead Ends

Common approaches that don't work:

  1. Switching to another RMW implementation (e.g., rmw_cyclonedds_cpp) blindly without testing message compatibility 70% fail

    The error is specific to the message type, not the RMW. Other RMWs may have similar limitations for complex types.

  2. Removing all fields from the message type to make it simpler, losing functionality 50% fail

    Overly aggressive simplification may break application logic; the type may still be unsupported if any problematic field remains.