ERROR ros2 communication_error ai_generated true

[ERROR] create_subscription(): type mismatch for topic '/cmd_vel'

ID: ros2/topic-type-mismatch

Also available as: JSON · Markdown
90%Fix Rate
88%Confidence
3Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
2 active — — —

Root Cause

Publisher and subscriber use different message types on the same topic name.

generic

Workarounds

  1. 95% success Check actual topic type with ros2 topic info 
    ros2 topic info /cmd_vel --verbose  # shows type for each publisher/subscriber
  2. 92% success Ensure both nodes import the same message package and type 
    from geometry_msgs.msg import Twist  # must match on both sides
  3. 85% success Use ros2 interface show to inspect the message definition 
    ros2 interface show geometry_msgs/msg/Twist

Dead Ends

Common approaches that don't work:

  1. Change one side's message type without updating the other 85% fail

    Causes the same error on the other node; both must agree on the exact message type

  2. Use a generic Any type or raw bytes 92% fail

    ROS 2 does not support untyped topics; DDS requires concrete IDL types for serialization

Error Chain

Frequently confused with: